21012222100 has 72 divisors (see below), whose sum is σ = 45859326968. Its totient is φ = 8356608000.

The previous prime is 21012222059. The next prime is 21012222109. The reversal of 21012222100 is 122221012.

It is a happy number.

It can be written as a sum of positive squares in 12 ways, for example, as 14623097476 + 6389124624 = 120926^2 + 79932^2 .

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21012222109) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 18810742 + ... + 18811858.

Almost surely, 2^21012222100 is an apocalyptic number.

21012222100 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21012222100 is an abundant number, since it is smaller than the sum of its proper divisors (24847104868).

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

21012222100 is a wasteful number, since it uses less digits than its factorization.

21012222100 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2045 (or 2038 counting only the distinct ones).

The product of its (nonzero) digits is 32, while the sum is 13.

Adding to 21012222100 its reverse (122221012), we get a palindrome (21134443112).

The spelling of 21012222100 in words is "twenty-one billion, twelve million, two hundred twenty-two thousand, one hundred".