21631894 has 8 divisors (see below), whose sum is σ = 32479488. Its totient is φ = 10805400.

The previous prime is 21631879. The next prime is 21631903. The reversal of 21631894 is 49813612.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 2397 + ... + 7000.

It is an arithmetic number, because the mean of its divisors is an integer number (4059936).

Almost surely, 2^21631894 is an apocalyptic number.

21631894 is a deficient number, since it is larger than the sum of its proper divisors (10847594).

21631894 is a wasteful number, since it uses less digits than its factorization.

21631894 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 10550.

The product of its digits is 10368, while the sum is 34.

The square root of 21631894 is about 4651.0099978392. The cubic root of 21631894 is about 278.6323356006.

The spelling of 21631894 in words is "twenty-one million, six hundred thirty-one thousand, eight hundred ninety-four".