21696872479 has 4 divisors (see below), whose sum is σ = 21698539200. Its totient is φ = 21695205760.

The previous prime is 21696872467. The next prime is 21696872501. The reversal of 21696872479 is 97427869612.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 21696872479 - 2²¹ = 21694775327 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 (21696872429) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 813679 + ... + 839920.

It is an arithmetic number, because the mean of its divisors is an integer number (5424634800).

Almost surely, 2^21696872479 is an apocalyptic number.

21696872479 is a deficient number, since it is larger than the sum of its proper divisors (1666721).

21696872479 is a wasteful number, since it uses less digits than its factorization.

21696872479 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1666720.

The product of its digits is 18289152, while the sum is 61.

The spelling of 21696872479 in words is "twenty-one billion, six hundred ninety-six million, eight hundred seventy-two thousand, four hundred seventy-nine".