21667526605 has 4 divisors (see below), whose sum is σ = 26001031932. Its totient is φ = 17334021280.

The previous prime is 21667526597. The next prime is 21667526627. The reversal of 21667526605 is 50662576612.

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

It can be written as a sum of positive squares in 2 ways, for example, as 15044984964 + 6622541641 = 122658^2 + 81379^2 .

It is not a de Polignac number, because 21667526605 - 2³ = 21667526597 is a prime.

It is a Duffinian number.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 2166752656 + ... + 2166752665.

It is an arithmetic number, because the mean of its divisors is an integer number (6500257983).

Almost surely, 2^21667526605 is an apocalyptic number.

It is an amenable number.

21667526605 is a deficient number, since it is larger than the sum of its proper divisors (4333505327).

21667526605 is an equidigital number, since it uses as much as digits as its factorization.

21667526605 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4333505326.

The product of its (nonzero) digits is 907200, while the sum is 46.

The spelling of 21667526605 in words is "twenty-one billion, six hundred sixty-seven million, five hundred twenty-six thousand, six hundred five".