21631197 has 12 divisors (see below), whose sum is σ = 33550656. Its totient is φ = 12360600.

The previous prime is 21631171. The next prime is 21631213. The reversal of 21631197 is 79113612.

It is not a de Polignac number, because 21631197 - 2¹² = 21627101 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21631297) by changing a digit.

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 11 ways as a sum of consecutive naturals, for example, 73429 + ... + 73722.

It is an arithmetic number, because the mean of its divisors is an integer number (2795888).

Almost surely, 2^21631197 is an apocalyptic number.

It is an amenable number.

21631197 is a deficient number, since it is larger than the sum of its proper divisors (11919459).

21631197 is a wasteful number, since it uses less digits than its factorization.

21631197 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 147168 (or 147161 counting only the distinct ones).

The product of its digits is 2268, while the sum is 30.

The square root of 21631197 is about 4650.9350672741. The cubic root of 21631197 is about 278.6293429697.

It can be divided in two parts, 216 and 31197, that added together give a palindrome (31413).

The spelling of 21631197 in words is "twenty-one million, six hundred thirty-one thousand, one hundred ninety-seven".