21126525665 has 48 divisors (see below), whose sum is σ = 30644568000. Its totient is φ = 13924536192.

The previous prime is 21126525643. The next prime is 21126525683. The reversal of 21126525665 is 56652562112.

It is not a de Polignac number, because 21126525665 - 2¹⁰ = 21126524641 is a prime.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 1606286 + ... + 1619384.

It is an arithmetic number, because the mean of its divisors is an integer number (638428500).

Almost surely, 2^21126525665 is an apocalyptic number.

It is an amenable number.

21126525665 is a deficient number, since it is larger than the sum of its proper divisors (9518042335).

21126525665 is a wasteful number, since it uses less digits than its factorization.

21126525665 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 13374 (or 13367 counting only the distinct ones).

The product of its digits is 216000, while the sum is 41.

The spelling of 21126525665 in words is "twenty-one billion, one hundred twenty-six million, five hundred twenty-five thousand, six hundred sixty-five".