21638446 has 16 divisors (see below), whose sum is σ = 34205184. Its totient is φ = 10246104.

The previous prime is 21638431. The next prime is 21638479. The reversal of 21638446 is 64483612.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 2455 + ... + 7021.

It is an arithmetic number, because the mean of its divisors is an integer number (2137824).

Almost surely, 2^21638446 is an apocalyptic number.

21638446 is a deficient number, since it is larger than the sum of its proper divisors (12566738).

21638446 is a wasteful number, since it uses less digits than its factorization.

21638446 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4695.

The product of its digits is 27648, while the sum is 34.

The square root of 21638446 is about 4651.7143076505. The cubic root of 21638446 is about 278.6604640480.

It can be divided in two parts, 2163 and 8446, that added together give a square (10609 = 103²).

The spelling of 21638446 in words is "twenty-one million, six hundred thirty-eight thousand, four hundred forty-six".