21791811591 has 96 divisors (see below), whose sum is σ = 37352689920. Its totient is φ = 12573792000.

The previous prime is 21791811571. The next prime is 21791811653. The reversal of 21791811591 is 19511819712.

It is not a de Polignac number, because 21791811591 - 2⁶ = 21791811527 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21791811551) by changing a digit.

It is a polite number, since it can be written in 95 ways as a sum of consecutive naturals, for example, 5656816 + ... + 5660666.

It is an arithmetic number, because the mean of its divisors is an integer number (389090520).

Almost surely, 2^21791811591 is an apocalyptic number.

21791811591 is a deficient number, since it is larger than the sum of its proper divisors (15560878329).

21791811591 is a wasteful number, since it uses less digits than its factorization.

21791811591 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3979 (or 3967 counting only the distinct ones).

The product of its digits is 45360, while the sum is 45.

The spelling of 21791811591 in words is "twenty-one billion, seven hundred ninety-one million, eight hundred eleven thousand, five hundred ninety-one".