21123535220 has 24 divisors (see below), whose sum is σ = 44751990024. Its totient is φ = 8374639616.

The previous prime is 21123535207. The next prime is 21123535231. The reversal of 21123535220 is 2253532112.

It is a happy number.

It can be written as a sum of positive squares in 4 ways, for example, as 213218404 + 20910316816 = 14602^2 + 144604^2 .

It is a self number, because there is not a number n which added to its sum of digits gives 21123535220.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 4671089 + ... + 4675608.

It is an arithmetic number, because the mean of its divisors is an integer number (1864666251).

Almost surely, 2^21123535220 is an apocalyptic number.

21123535220 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21123535220 is an abundant number, since it is smaller than the sum of its proper divisors (23628454804).

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

21123535220 is a wasteful number, since it uses less digits than its factorization.

21123535220 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 9346819 (or 9346817 counting only the distinct ones).

The product of its (nonzero) digits is 3600, while the sum is 26.

The spelling of 21123535220 in words is "twenty-one billion, one hundred twenty-three million, five hundred thirty-five thousand, two hundred twenty".