21001012320 has 96 divisors (see below), whose sum is σ = 66194483040. Its totient is φ = 5596774400.

The previous prime is 21001012313. The next prime is 21001012367. The reversal of 21001012320 is 2321010012.

It is a tau number, because it is divible by the number of its divisors (96).

It is a Harshad number since it is a multiple of its sum of digits (12).

It is a junction number, because it is equal to n+sod(n) for n = 21001012296 and 21001012305.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 807520 + ... + 833120.

It is an arithmetic number, because the mean of its divisors is an integer number (689525865).

Almost surely, 2^21001012320 is an apocalyptic number.

21001012320 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21001012320 is an abundant number, since it is smaller than the sum of its proper divisors (45193470720).

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

21001012320 is a wasteful number, since it uses less digits than its factorization.

21001012320 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 27328 (or 27320 counting only the distinct ones).

The product of its (nonzero) digits is 24, while the sum is 12.

Adding to 21001012320 its reverse (2321010012), we get a palindrome (23322022332).

The spelling of 21001012320 in words is "twenty-one billion, one million, twelve thousand, three hundred twenty".