21021011220 has 48 divisors (see below), whose sum is σ = 64209636288. Its totient is φ = 5096002560.

The previous prime is 21021011213. The next prime is 21021011239. The reversal of 21021011220 is 2211012012.

It is a super-2 number, since 2×21021011220² (a number of 21 digits) contains 22 as substring.

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 = 21021011196 and 21021011205.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 15924349 + ... + 15925668.

It is an arithmetic number, because the mean of its divisors is an integer number (1337700756).

Almost surely, 2^21021011220 is an apocalyptic number.

21021011220 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21021011220 is an abundant number, since it is smaller than the sum of its proper divisors (43188625068).

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

21021011220 is a wasteful number, since it uses less digits than its factorization.

21021011220 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 31850040 (or 31850038 counting only the distinct ones).

The product of its (nonzero) digits is 16, while the sum is 12.

Adding to 21021011220 its reverse (2211012012), we get a palindrome (23232023232).

The spelling of 21021011220 in words is "twenty-one billion, twenty-one million, eleven thousand, two hundred twenty".