21012550400 has 54 divisors (see below), whose sum is σ = 52009361292. Its totient is φ = 8405017600.

The previous prime is 21012550373. The next prime is 21012550483. The reversal of 21012550400 is 405521012.

It is a Harshad number since it is a multiple of its sum of digits (20).

It is an unprimeable number.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 1635206 + ... + 1648005.

Almost surely, 2^21012550400 is an apocalyptic number.

21012550400 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21012550400 is an abundant number, since it is smaller than the sum of its proper divisors (30996810892).

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

21012550400 is an equidigital number, since it uses as much as digits as its factorization.

21012550400 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3283237 (or 3283218 counting only the distinct ones).

The product of its (nonzero) digits is 400, while the sum is 20.

The spelling of 21012550400 in words is "twenty-one billion, twelve million, five hundred fifty thousand, four hundred".