21683638 has 16 divisors (see below), whose sum is σ = 33359040. Its totient is φ = 10566016.

The previous prime is 21683611. The next prime is 21683659. The reversal of 21683638 is 83638612.

It is a plaindrome in base 8.

It is a junction number, because it is equal to n+sod(n) for n = 21683597 and 21683606.

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, 36270 + ... + 36862.

It is an arithmetic number, because the mean of its divisors is an integer number (2084940).

Almost surely, 2^21683638 is an apocalyptic number.

21683638 is a deficient number, since it is larger than the sum of its proper divisors (11675402).

21683638 is a wasteful number, since it uses less digits than its factorization.

21683638 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1031.

The product of its digits is 41472, while the sum is 37.

The square root of 21683638 is about 4656.5693380428. The cubic root of 21683638 is about 278.8543237310.

The spelling of 21683638 in words is "twenty-one million, six hundred eighty-three thousand, six hundred thirty-eight".