21550520400 has 60 divisors (see below), whose sum is σ = 69033504192. Its totient is φ = 5746805120.

The previous prime is 21550520353. The next prime is 21550520413. The reversal of 21550520400 is 402505512.

It is a happy number.

It is a tau number, because it is divible by the number of its divisors (60).

It is a Harshad number since it is a multiple of its sum of digits (24).

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 8978184 + ... + 8980583.

Almost surely, 2^21550520400 is an apocalyptic number.

21550520400 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21550520400 is an abundant number, since it is smaller than the sum of its proper divisors (47482983792).

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

21550520400 is a wasteful number, since it uses less digits than its factorization.

21550520400 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 17958788 (or 17958777 counting only the distinct ones).

The product of its (nonzero) digits is 2000, while the sum is 24.

The spelling of 21550520400 in words is "twenty-one billion, five hundred fifty million, five hundred twenty thousand, four hundred".