21165135744 has 32 divisors (see below), whose sum is σ = 56219892840. Its totient is φ = 7055045120.

The previous prime is 21165135707. The next prime is 21165135751. The reversal of 21165135744 is 44753156112.

It is a tau number, because it is divible by the number of its divisors (32).

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 27558387 + ... + 27559154.

Almost surely, 2^21165135744 is an apocalyptic number.

21165135744 is a gapful number since it is divisible by the number (24) formed by its first and last digit.

It is an amenable number.

21165135744 is an abundant number, since it is smaller than the sum of its proper divisors (35054757096).

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

21165135744 is an equidigital number, since it uses as much as digits as its factorization.

21165135744 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 55117558 (or 55117546 counting only the distinct ones).

The product of its digits is 100800, while the sum is 39.

The spelling of 21165135744 in words is "twenty-one billion, one hundred sixty-five million, one hundred thirty-five thousand, seven hundred forty-four".