21640673279 has 8 divisors (see below), whose sum is σ = 22296703680. Its totient is φ = 20992792576.

The previous prime is 21640673239. The next prime is 21640673287. The reversal of 21640673279 is 97237604612.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 21640673279 - 2²⁸ = 21372237823 is a prime.

It is a super-2 number, since 2×21640673279² (a number of 21 digits) contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (47).

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21640673239) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 2032034 + ... + 2042655.

It is an arithmetic number, because the mean of its divisors is an integer number (2787087960).

Almost surely, 2^21640673279 is an apocalyptic number.

21640673279 is a deficient number, since it is larger than the sum of its proper divisors (656030401).

21640673279 is a wasteful number, since it uses less digits than its factorization.

21640673279 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4074849.

The product of its (nonzero) digits is 762048, while the sum is 47.

The spelling of 21640673279 in words is "twenty-one billion, six hundred forty million, six hundred seventy-three thousand, two hundred seventy-nine".