21261079553 has 16 divisors (see below), whose sum is σ = 25589760000. Its totient is φ = 17256184272.

The previous prime is 21261079523. The next prime is 21261079559. The reversal of 21261079553 is 35597016212.

It is a cyclic number.

It is not a de Polignac number, because 21261079553 - 2⁸ = 21261079297 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 21261079553.

It is not an unprimeable number, because it can be changed into a prime (21261079559) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 241088 + ... + 317246.

It is an arithmetic number, because the mean of its divisors is an integer number (1599360000).

Almost surely, 2^21261079553 is an apocalyptic number.

It is an amenable number.

21261079553 is a deficient number, since it is larger than the sum of its proper divisors (4328680447).

21261079553 is a wasteful number, since it uses less digits than its factorization.

21261079553 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 78284.

The product of its (nonzero) digits is 113400, while the sum is 41.

The spelling of 21261079553 in words is "twenty-one billion, two hundred sixty-one million, seventy-nine thousand, five hundred fifty-three".