21312223020 has 144 divisors (see below), whose sum is σ = 71317078560. Its totient is φ = 5108505600.

The previous prime is 21312223019. The next prime is 21312223033. The reversal of 21312223020 is 2032221312.

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 = 21312222984 and 21312223002.

It is an unprimeable number.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 115750 + ... + 236690.

It is an arithmetic number, because the mean of its divisors is an integer number (495257490).

Almost surely, 2^21312223020 is an apocalyptic number.

21312223020 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 21312223020, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (35658539280).

21312223020 is an abundant number, since it is smaller than the sum of its proper divisors (50004855540).

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

21312223020 is a wasteful number, since it uses less digits than its factorization.

21312223020 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 121056 (or 121051 counting only the distinct ones).

The product of its (nonzero) digits is 288, while the sum is 18.

Adding to 21312223020 its reverse (2032221312), we get a palindrome (23344444332).

The spelling of 21312223020 in words is "twenty-one billion, three hundred twelve million, two hundred twenty-three thousand, twenty".