21904576491 has 16 divisors (see below), whose sum is σ = 33393394944. Its totient is φ = 12511278624.

The previous prime is 21904576489. The next prime is 21904576501. The reversal of 21904576491 is 19467540912.

It is a happy number.

It is not a de Polignac number, because 21904576491 - 2¹ = 21904576489 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 21904576491.

It is not an unprimeable number, because it can be changed into a prime (21904576411) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 186165 + ... + 280118.

It is an arithmetic number, because the mean of its divisors is an integer number (2087087184).

Almost surely, 2^21904576491 is an apocalyptic number.

21904576491 is a gapful number since it is divisible by the number (21) formed by its first and last digit.

21904576491 is a deficient number, since it is larger than the sum of its proper divisors (11488818453).

21904576491 is a wasteful number, since it uses less digits than its factorization.

21904576491 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 468530.

The product of its (nonzero) digits is 544320, while the sum is 48.

The spelling of 21904576491 in words is "twenty-one billion, nine hundred four million, five hundred seventy-six thousand, four hundred ninety-one".