21152691 has 16 divisors (see below), whose sum is σ = 35814400. Its totient is φ = 12087144.

The previous prime is 21152683. The next prime is 21152713. The reversal of 21152691 is 19625112.

It is not a de Polignac number, because 21152691 - 2³ = 21152683 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (27).

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21152291) 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, 55771 + ... + 56148.

It is an arithmetic number, because the mean of its divisors is an integer number (2238400).

Almost surely, 2^21152691 is an apocalyptic number.

21152691 is a gapful number since it is divisible by the number (21) formed by its first and last digit.

21152691 is a deficient number, since it is larger than the sum of its proper divisors (14661709).

21152691 is a wasteful number, since it uses less digits than its factorization.

21152691 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 111935 (or 111929 counting only the distinct ones).

The product of its digits is 1080, while the sum is 27.

The square root of 21152691 is about 4599.2054748619. The cubic root of 21152691 is about 276.5594747730.

The spelling of 21152691 in words is "twenty-one million, one hundred fifty-two thousand, six hundred ninety-one".