21631366 has 16 divisors (see below), whose sum is σ = 33644160. Its totient is φ = 10419840.

The previous prime is 21631349. The next prime is 21631387. The reversal of 21631366 is 66313612.

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, 16030 + ... + 17326.

It is an arithmetic number, because the mean of its divisors is an integer number (2102760).

Almost surely, 2^21631366 is an apocalyptic number.

21631366 is a deficient number, since it is larger than the sum of its proper divisors (12012794).

21631366 is a wasteful number, since it uses less digits than its factorization.

21631366 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1599.

The product of its digits is 3888, while the sum is 28.

The square root of 21631366 is about 4650.9532356282. The cubic root of 21631366 is about 278.6300685920.

Adding to 21631366 its reverse (66313612), we get a palindrome (87944978).

The spelling of 21631366 in words is "twenty-one million, six hundred thirty-one thousand, three hundred sixty-six".