21312331220 has 48 divisors (see below), whose sum is σ = 45139852800. Its totient is φ = 8452012416.

The previous prime is 21312331171. The next prime is 21312331223. The reversal of 21312331220 is 2213321312.

It is a Harshad number since it is a multiple of its sum of digits (20).

It is a junction number, because it is equal to n+sod(n) for n = 21312331192 and 21312331201.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21312331223) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 1671389 + ... + 1684091.

It is an arithmetic number, because the mean of its divisors is an integer number (940413600).

Almost surely, 2^21312331220 is an apocalyptic number.

21312331220 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21312331220 is an abundant number, since it is smaller than the sum of its proper divisors (23827521580).

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

21312331220 is a wasteful number, since it uses less digits than its factorization.

21312331220 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 13424 (or 13422 counting only the distinct ones).

The product of its (nonzero) digits is 432, while the sum is 20.

Adding to 21312331220 its reverse (2213321312), we get a palindrome (23525652532).

The spelling of 21312331220 in words is "twenty-one billion, three hundred twelve million, three hundred thirty-one thousand, two hundred twenty".