21420323320 has 128 divisors (see below), whose sum is σ = 53961292800. Its totient is φ = 7585804800.

The previous prime is 21420323311. The next prime is 21420323329. The reversal of 21420323320 is 2332302412.

It is an interprime number because it is at equal distance from previous prime (21420323311) and next prime (21420323329).

It is a super-2 number, since 2×21420323320² (a number of 21 digits) contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (22).

It is a junction number, because it is equal to n+sod(n) for n = 21420323291 and 21420323300.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21420323329) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 4361026 + ... + 4365934.

It is an arithmetic number, because the mean of its divisors is an integer number (421572600).

Almost surely, 2^21420323320 is an apocalyptic number.

21420323320 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21420323320, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (26980646400).

21420323320 is an abundant number, since it is smaller than the sum of its proper divisors (32540969480).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

21420323320 is a wasteful number, since it uses less digits than its factorization.

21420323320 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 5189 (or 5185 counting only the distinct ones).

The product of its (nonzero) digits is 1728, while the sum is 22.

Adding to 21420323320 its reverse (2332302412), we get a palindrome (23752625732).

The spelling of 21420323320 in words is "twenty-one billion, four hundred twenty million, three hundred twenty-three thousand, three hundred twenty".