21133951820 has 12 divisors (see below), whose sum is σ = 44381298864. Its totient is φ = 8453580720.

The previous prime is 21133951801. The next prime is 21133951823. The reversal of 21133951820 is 2815933112.

It is not an unprimeable number, because it can be changed into a prime (21133951823) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 528348776 + ... + 528348815.

It is an arithmetic number, because the mean of its divisors is an integer number (3698441572).

Almost surely, 2^21133951820 is an apocalyptic number.

21133951820 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21133951820 is an abundant number, since it is smaller than the sum of its proper divisors (23247347044).

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

21133951820 is a wasteful number, since it uses less digits than its factorization.

21133951820 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1056697600 (or 1056697598 counting only the distinct ones).

The product of its (nonzero) digits is 12960, while the sum is 35.

The spelling of 21133951820 in words is "twenty-one billion, one hundred thirty-three million, nine hundred fifty-one thousand, eight hundred twenty".