21012212100 has 144 divisors (see below), whose sum is σ = 69813031680. Its totient is φ = 4825756800.

The previous prime is 21012212099. The next prime is 21012212153. The reversal of 21012212100 is 121221012.

It is a Harshad number since it is a multiple of its sum of digits (12).

It is an unprimeable number.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 104862 + ... + 230261.

It is an arithmetic number, because the mean of its divisors is an integer number (484812720).

Almost surely, 2^21012212100 is an apocalyptic number.

21012212100 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21012212100 is an abundant number, since it is smaller than the sum of its proper divisors (48800819580).

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

21012212100 is a wasteful number, since it uses less digits than its factorization.

21012212100 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 335170 (or 335163 counting only the distinct ones).

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

Adding to 21012212100 its reverse (121221012), we get a palindrome (21133433112).

It can be divided in two parts, 210122 and 12100, that added together give a palindrome (222222).

The spelling of 21012212100 in words is "twenty-one billion, twelve million, two hundred twelve thousand, one hundred".