21220312320 has 108 divisors (see below), whose sum is σ = 73420110036. Its totient is φ = 5658746880.

The previous prime is 21220312319. The next prime is 21220312343. The reversal of 21220312320 is 2321302212.

21220312320 is a `hidden beast` number, since 2 + 12 + 20 + 312 + 320 = 666.

It can be written as a sum of positive squares in 2 ways, for example, as 2387690496 + 18832621824 = 48864^2 + 137232^2 .

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 = 21220312293 and 21220312302.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 909501 + ... + 932540.

Almost surely, 2^21220312320 is an apocalyptic number.

21220312320 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21220312320 is an abundant number, since it is smaller than the sum of its proper divisors (52199797716).

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

21220312320 is a wasteful number, since it uses less digits than its factorization.

21220312320 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1842068 (or 1842051 counting only the distinct ones).

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

Adding to 21220312320 its reverse (2321302212), we get a palindrome (23541614532).

The spelling of 21220312320 in words is "twenty-one billion, two hundred twenty million, three hundred twelve thousand, three hundred twenty".