21123204100 has 36 divisors (see below), whose sum is σ = 46955346228. Its totient is φ = 8243200000.

The previous prime is 21123204097. The next prime is 21123204103. The reversal of 21123204100 is 140232112.

It is an interprime number because it is at equal distance from previous prime (21123204097) and next prime (21123204103).

It can be written as a sum of positive squares in 6 ways, for example, as 6106172164 + 15017031936 = 78142^2 + 122544^2 .

It is not an unprimeable number, because it can be changed into a prime (21123204103) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 2571901 + ... + 2580100.

It is an arithmetic number, because the mean of its divisors is an integer number (1304315173).

Almost surely, 2^21123204100 is an apocalyptic number.

21123204100 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21123204100 is an abundant number, since it is smaller than the sum of its proper divisors (25832142128).

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

21123204100 is a wasteful number, since it uses less digits than its factorization.

21123204100 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 5152056 (or 5152049 counting only the distinct ones).

The product of its (nonzero) digits is 96, while the sum is 16.

Adding to 21123204100 its reverse (140232112), we get a palindrome (21263436212).

The spelling of 21123204100 in words is "twenty-one billion, one hundred twenty-three million, two hundred four thousand, one hundred".