21012210020 has 48 divisors (see below), whose sum is σ = 44791584768. Its totient is φ = 8278273920.

The previous prime is 21012210013. The next prime is 21012210049. The reversal of 21012210020 is 2001221012.

It is a happy number.

It is a junction number, because it is equal to n+sod(n) for n = 21012209983 and 21012210010.

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, 1536734 + ... + 1550346.

It is an arithmetic number, because the mean of its divisors is an integer number (933158016).

Almost surely, 2^21012210020 is an apocalyptic number.

21012210020 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21012210020 is an abundant number, since it is smaller than the sum of its proper divisors (23779374748).

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

21012210020 is a wasteful number, since it uses less digits than its factorization.

21012210020 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 14780 (or 14778 counting only the distinct ones).

The product of its (nonzero) digits is 16, while the sum is 11.

Adding to 21012210020 its reverse (2001221012), we get a palindrome (23013431032).

The spelling of 21012210020 in words is "twenty-one billion, twelve million, two hundred ten thousand, twenty".