21421021320 has 128 divisors (see below), whose sum is σ = 72110736000. Its totient is φ = 5655686400.

The previous prime is 21421021291. The next prime is 21421021333. The reversal of 21421021320 is 2312012412.

It is a happy number.

It is a Harshad number since it is a multiple of its sum of digits (18).

It is a junction number, because it is equal to n+sod(n) for n = 21421021293 and 21421021302.

It is an unprimeable number.

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, 10891 + ... + 207269.

It is an arithmetic number, because the mean of its divisors is an integer number (563365125).

Almost surely, 2^21421021320 is an apocalyptic number.

21421021320 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 21421021320, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (36055368000).

21421021320 is an abundant number, since it is smaller than the sum of its proper divisors (50689714680).

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

21421021320 is a wasteful number, since it uses less digits than its factorization.

21421021320 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 196500 (or 196490 counting only the distinct ones).

The product of its (nonzero) digits is 192, while the sum is 18.

Adding to 21421021320 its reverse (2312012412), we get a palindrome (23733033732).

The spelling of 21421021320 in words is "twenty-one billion, four hundred twenty-one million, twenty-one thousand, three hundred twenty".