21691179 has 16 divisors (see below), whose sum is σ = 33827200. Its totient is φ = 13699368.

The previous prime is 21691177. The next prime is 21691193. The reversal of 21691179 is 97119612.

It is not a de Polignac number, because 21691179 - 2¹ = 21691177 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21691171) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 20629 + ... + 21654.

It is an arithmetic number, because the mean of its divisors is an integer number (2114200).

Almost surely, 2^21691179 is an apocalyptic number.

21691179 is a deficient number, since it is larger than the sum of its proper divisors (12136021).

21691179 is a wasteful number, since it uses less digits than its factorization.

21691179 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 42311 (or 42305 counting only the distinct ones).

The product of its digits is 6804, while the sum is 36.

The square root of 21691179 is about 4657.3789839351. The cubic root of 21691179 is about 278.8866460552.

The spelling of 21691179 in words is "twenty-one million, six hundred ninety-one thousand, one hundred seventy-nine".