21031220220 has 48 divisors (see below), whose sum is σ = 59437784448. Its totient is φ = 5555909440.

The previous prime is 21031220219. The next prime is 21031220257. The reversal of 21031220220 is 2202213012.

It is a happy number.

It is a Harshad number since it is a multiple of its sum of digits (15).

It is a self number, because there is not a number n which added to its sum of digits gives 21031220220.

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, 1631526 + ... + 1644365.

It is an arithmetic number, because the mean of its divisors is an integer number (1238287176).

Almost surely, 2^21031220220 is an apocalyptic number.

21031220220 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21031220220 is an abundant number, since it is smaller than the sum of its proper divisors (38406564228).

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

21031220220 is a wasteful number, since it uses less digits than its factorization.

21031220220 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3276010 (or 3276008 counting only the distinct ones).

The product of its (nonzero) digits is 96, while the sum is 15.

Adding to 21031220220 its reverse (2202213012), we get a palindrome (23233433232).

The spelling of 21031220220 in words is "twenty-one billion, thirty-one million, two hundred twenty thousand, two hundred twenty".