21691065 has 96 divisors (see below), whose sum is σ = 43666560. Its totient is φ = 9123840.

The previous prime is 21691037. The next prime is 21691067. The reversal of 21691065 is 56019612.

It is not a de Polignac number, because 21691065 - 2⁹ = 21690553 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21691067) by changing a digit.

It is a polite number, since it can be written in 95 ways as a sum of consecutive naturals, for example, 586227 + ... + 586263.

It is an arithmetic number, because the mean of its divisors is an integer number (454860).

Almost surely, 2^21691065 is an apocalyptic number.

It is an amenable number.

21691065 is a primitive abundant number, since it is smaller than the sum of its proper divisors, none of which is abundant.

21691065 is a wasteful number, since it uses less digits than its factorization.

21691065 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 103 (or 92 counting only the distinct ones).

The product of its (nonzero) digits is 3240, while the sum is 30.

The square root of 21691065 is about 4657.3667452757. The cubic root of 21691065 is about 278.8861574828.

The spelling of 21691065 in words is "twenty-one million, six hundred ninety-one thousand, sixty-five".