21311031220 has 24 divisors (see below), whose sum is σ = 46196817408. Its totient is φ = 8249431200.

The previous prime is 21311031167. The next prime is 21311031233. The reversal of 21311031220 is 2213011312.

It is a junction number, because it is equal to n+sod(n) for n = 21311031194 and 21311031203.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 17185696 + ... + 17186935.

It is an arithmetic number, because the mean of its divisors is an integer number (1924867392).

Almost surely, 2^21311031220 is an apocalyptic number.

21311031220 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21311031220 is an abundant number, since it is smaller than the sum of its proper divisors (24885786188).

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

21311031220 is a wasteful number, since it uses less digits than its factorization.

21311031220 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 34372671 (or 34372669 counting only the distinct ones).

The product of its (nonzero) digits is 72, while the sum is 16.

Adding to 21311031220 its reverse (2213011312), we get a palindrome (23524042532).

The spelling of 21311031220 in words is "twenty-one billion, three hundred eleven million, thirty-one thousand, two hundred twenty".