21606724 has 24 divisors (see below), whose sum is σ = 40188960. Its totient is φ = 10135296.

The previous prime is 21606719. The next prime is 21606727. The reversal of 21606724 is 42760612.

It is a junction number, because it is equal to n+sod(n) for n = 21606692 and 21606701.

It is not an unprimeable number, because it can be changed into a prime (21606727) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 6804 + ... + 9460.

It is an arithmetic number, because the mean of its divisors is an integer number (1674540).

Almost surely, 2^21606724 is an apocalyptic number.

It is an amenable number.

21606724 is a deficient number, since it is larger than the sum of its proper divisors (18582236).

21606724 is a wasteful number, since it uses less digits than its factorization.

21606724 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2787 (or 2785 counting only the distinct ones).

The product of its (nonzero) digits is 4032, while the sum is 28.

The square root of 21606724 is about 4648.3033463835. The cubic root of 21606724 is about 278.5242252069.

The spelling of 21606724 in words is "twenty-one million, six hundred six thousand, seven hundred twenty-four".