21909197871 has 96 divisors (see below), whose sum is σ = 36857811200. Its totient is φ = 12843230400.

The previous prime is 21909197857. The next prime is 21909197873. The reversal of 21909197871 is 17879190912.

It is not a de Polignac number, because 21909197871 - 2¹⁴ = 21909181487 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21909197873) by changing a digit.

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 95 ways as a sum of consecutive naturals, for example, 25505040 + ... + 25505898.

Almost surely, 2^21909197871 is an apocalyptic number.

21909197871 is a deficient number, since it is larger than the sum of its proper divisors (14948613329).

21909197871 is a wasteful number, since it uses less digits than its factorization.

21909197871 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1138 (or 1121 counting only the distinct ones).

The product of its (nonzero) digits is 571536, while the sum is 54.

The spelling of 21909197871 in words is "twenty-one billion, nine hundred nine million, one hundred ninety-seven thousand, eight hundred seventy-one".