21215632 has 10 divisors (see below), whose sum is σ = 41105318. Its totient is φ = 10607808.

The previous prime is 21215627. The next prime is 21215657. The reversal of 21215632 is 23651212.

It can be written as a sum of positive squares in only one way, i.e., 21123216 + 92416 = 4596^2 + 304^2 .

It is an unprimeable number.

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 as a sum of consecutive naturals, namely, 662973 + ... + 663004.

Almost surely, 2^21215632 is an apocalyptic number.

It is an amenable number.

21215632 is a deficient number, since it is larger than the sum of its proper divisors (19889686).

21215632 is a wasteful number, since it uses less digits than its factorization.

21215632 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1325985 (or 1325979 counting only the distinct ones).

The product of its digits is 720, while the sum is 22.

The square root of 21215632 is about 4606.0429872071. The cubic root of 21215632 is about 276.8335091467.

Adding to 21215632 its reverse (23651212), we get a palindrome (44866844).

The spelling of 21215632 in words is "twenty-one million, two hundred fifteen thousand, six hundred thirty-two".