21692881 has 16 divisors (see below), whose sum is σ = 25498368. Its totient is φ = 18072000.

The previous prime is 21692857. The next prime is 21692903. The reversal of 21692881 is 18829612.

It is a cyclic number.

It is not a de Polignac number, because 21692881 - 2⁵ = 21692849 is a prime.

It is a super-2 number, since 2×21692881² = 941162172160322, which contains 22 as substring.

It is a self number, because there is not a number n which added to its sum of digits gives 21692881.

It is not an unprimeable number, because it can be changed into a prime (21692681) 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, 42876 + ... + 43378.

It is an arithmetic number, because the mean of its divisors is an integer number (1593648).

Almost surely, 2^21692881 is an apocalyptic number.

It is an amenable number.

21692881 is a deficient number, since it is larger than the sum of its proper divisors (3805487).

21692881 is a wasteful number, since it uses less digits than its factorization.

21692881 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 672.

The product of its digits is 13824, while the sum is 37.

The square root of 21692881 is about 4657.5617011479. The cubic root of 21692881 is about 278.8939401517.

It can be divided in two parts, 2169 and 2881, that added together give a triangular number (5050 = T₁₀₀).

The spelling of 21692881 in words is "twenty-one million, six hundred ninety-two thousand, eight hundred eighty-one".