21731507667 has 6 divisors (see below), whose sum is σ = 31389955532. Its totient is φ = 14487671772.

The previous prime is 21731507647. The next prime is 21731507669. The reversal of 21731507667 is 76670513712.

It is not a de Polignac number, because 21731507667 - 2⁸ = 21731507411 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21731507669) by changing a digit.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 1207305973 + ... + 1207305990.

Almost surely, 2^21731507667 is an apocalyptic number.

21731507667 is a deficient number, since it is larger than the sum of its proper divisors (9658447865).

21731507667 is a wasteful number, since it uses less digits than its factorization.

21731507667 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2414611969 (or 2414611966 counting only the distinct ones).

The product of its (nonzero) digits is 370440, while the sum is 45.

The spelling of 21731507667 in words is "twenty-one billion, seven hundred thirty-one million, five hundred seven thousand, six hundred sixty-seven".