21631444 has 6 divisors (see below), whose sum is σ = 37855034. Its totient is φ = 10815720.

The previous prime is 21631439. The next prime is 21631447. The reversal of 21631444 is 44413612.

It can be written as a sum of positive squares in only one way, i.e., 13046544 + 8584900 = 3612^2 + 2930^2 .

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21631447) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 2703927 + ... + 2703934.

Almost surely, 2^21631444 is an apocalyptic number.

It is an amenable number.

21631444 is a deficient number, since it is larger than the sum of its proper divisors (16223590).

21631444 is a wasteful number, since it uses less digits than its factorization.

21631444 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 5407865 (or 5407863 counting only the distinct ones).

The product of its digits is 2304, while the sum is 25.

The square root of 21631444 is about 4650.9616209984. The cubic root of 21631444 is about 278.6304034933.

The spelling of 21631444 in words is "twenty-one million, six hundred thirty-one thousand, four hundred forty-four".