21630724 has 12 divisors (see below), whose sum is σ = 37939804. Its totient is φ = 10790784.

The previous prime is 21630689. The next prime is 21630727. The reversal of 21630724 is 42703612.

It can be written as a sum of positive squares in 2 ways, for example, as 19642624 + 1988100 = 4432^2 + 1410^2 .

It is not an unprimeable number, because it can be changed into a prime (21630727) 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, 4089 + ... + 7744.

Almost surely, 2^21630724 is an apocalyptic number.

It is an amenable number.

21630724 is a deficient number, since it is larger than the sum of its proper divisors (16309080).

21630724 is a wasteful number, since it uses less digits than its factorization.

21630724 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 12294 (or 12292 counting only the distinct ones).

The product of its (nonzero) digits is 2016, while the sum is 25.

The square root of 21630724 is about 4650.8842170065. The cubic root of 21630724 is about 278.6273120659.

The spelling of 21630724 in words is "twenty-one million, six hundred thirty thousand, seven hundred twenty-four".