21260553654640 has 80 divisors (see below), whose sum is σ = 51493451708160. Its totient is φ = 8154388039680.

The previous prime is 21260553654631. The next prime is 21260553654653. The reversal of 21260553654640 is 4645635506212.

It is a tau number, because it is divible by the number of its divisors (80).

It is a super-2 number, since 2×21260553654640² (a number of 27 digits) contains 22 as substring.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 39054469 + ... + 39595108.

It is an arithmetic number, because the mean of its divisors is an integer number (643668146352).

Almost surely, 2^{21260553654640} is an apocalyptic number.

21260553654640 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21260553654640 is an abundant number, since it is smaller than the sum of its proper divisors (30232898053520).

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

21260553654640 is a wasteful number, since it uses less digits than its factorization.

21260553654640 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 78649730 (or 78649724 counting only the distinct ones).

The product of its (nonzero) digits is 5184000, while the sum is 49.

The spelling of 21260553654640 in words is "twenty-one trillion, two hundred sixty billion, five hundred fifty-three million, six hundred fifty-four thousand, six hundred forty".