21165653634 has 32 divisors (see below), whose sum is σ = 42469405440. Its totient is φ = 7032241152.

The previous prime is 21165653603. The next prime is 21165653659. The reversal of 21165653634 is 43635656112.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 2450247 + ... + 2458869.

It is an arithmetic number, because the mean of its divisors is an integer number (1327168920).

Almost surely, 2^21165653634 is an apocalyptic number.

21165653634 is an abundant number, since it is smaller than the sum of its proper divisors (21303751806).

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

21165653634 is a wasteful number, since it uses less digits than its factorization.

21165653634 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 9914.

The product of its digits is 388800, while the sum is 42.

The spelling of 21165653634 in words is "twenty-one billion, one hundred sixty-five million, six hundred fifty-three thousand, six hundred thirty-four".