21565876553 has 12 divisors (see below), whose sum is σ = 23362778448. Its totient is φ = 19898115120.

The previous prime is 21565876537. The next prime is 21565876567. The reversal of 21565876553 is 35567856512.

It is not a de Polignac number, because 21565876553 - 2⁴ = 21565876537 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is a junction number, because it is equal to n+sod(n) for n = 21565876495 and 21565876504.

It is not an unprimeable number, because it can be changed into a prime (21565876513) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 369458 + ... + 423828.

It is an arithmetic number, because the mean of its divisors is an integer number (1946898204).

Almost surely, 2^21565876553 is an apocalyptic number.

It is an amenable number.

21565876553 is a deficient number, since it is larger than the sum of its proper divisors (1796901895).

21565876553 is a wasteful number, since it uses less digits than its factorization.

21565876553 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 56744 (or 56731 counting only the distinct ones).

The product of its digits is 7560000, while the sum is 53.

The spelling of 21565876553 in words is "twenty-one billion, five hundred sixty-five million, eight hundred seventy-six thousand, five hundred fifty-three".