21261021531600 has 120 divisors (see below), whose sum is σ = 69690002839072. Its totient is φ = 5537754432000.

The previous prime is 21261021531583. The next prime is 21261021531601. The reversal of 21261021531600 is 613512016212.

It is a tau number, because it is divible by the number of its divisors (120).

It is a Harshad number since it is a multiple of its sum of digits (30).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21261021531601) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (23) of ones.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 205966051 + ... + 206069250.

Almost surely, 2^{21261021531600} is an apocalyptic number.

21261021531600 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21261021531600 is an abundant number, since it is smaller than the sum of its proper divisors (48428981307472).

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

21261021531600 is a wasteful number, since it uses less digits than its factorization.

21261021531600 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 412035365 (or 412035354 counting only the distinct ones).

The product of its (nonzero) digits is 4320, while the sum is 30.

Adding to 21261021531600 its reverse (613512016212), we get a palindrome (21874533547812).

The spelling of 21261021531600 in words is "twenty-one trillion, two hundred sixty-one billion, twenty-one million, five hundred thirty-one thousand, six hundred".