21212012100 has 36 divisors (see below), whose sum is σ = 61373422544. Its totient is φ = 5656536480.

The previous prime is 21212012069. The next prime is 21212012141. The reversal of 21212012100 is 121021212.

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 11 ways as a sum of consecutive naturals, for example, 35353054 + ... + 35353653.

Almost surely, 2^21212012100 is an apocalyptic number.

21212012100 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21212012100 is an abundant number, since it is smaller than the sum of its proper divisors (40161410444).

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

21212012100 is a wasteful number, since it uses less digits than its factorization.

21212012100 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 70706724 (or 70706717 counting only the distinct ones).

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

Adding to 21212012100 its reverse (121021212), we get a palindrome (21333033312).

The spelling of 21212012100 in words is "twenty-one billion, two hundred twelve million, twelve thousand, one hundred".