21631436 has 12 divisors (see below), whose sum is σ = 38778600. Its totient is φ = 10551840.

The previous prime is 21631409. The next prime is 21631439. The reversal of 21631436 is 63413612.

It is not an unprimeable number, because it can be changed into a prime (21631439) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 65786 + ... + 66113.

It is an arithmetic number, because the mean of its divisors is an integer number (3231550).

Almost surely, 2^21631436 is an apocalyptic number.

It is an amenable number.

21631436 is a deficient number, since it is larger than the sum of its proper divisors (17147164).

21631436 is a wasteful number, since it uses less digits than its factorization.

21631436 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 131944 (or 131942 counting only the distinct ones).

The product of its digits is 2592, while the sum is 26.

The square root of 21631436 is about 4650.9607609611. The cubic root of 21631436 is about 278.6303691445.

The spelling of 21631436 in words is "twenty-one million, six hundred thirty-one thousand, four hundred thirty-six".