21365724 has 24 divisors (see below), whose sum is σ = 51201808. Its totient is φ = 6929280.

The previous prime is 21365723. The next prime is 21365737. The reversal of 21365724 is 42756312.

It is a junction number, because it is equal to n+sod(n) for n = 21365691 and 21365700.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21365723) by changing a digit.

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 in 7 ways as a sum of consecutive naturals, for example, 23617 + ... + 24504.

Almost surely, 2^21365724 is an apocalyptic number.

It is an amenable number.

21365724 is an abundant number, since it is smaller than the sum of its proper divisors (29836084).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

21365724 is a wasteful number, since it uses less digits than its factorization.

21365724 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 48165 (or 48163 counting only the distinct ones).

The product of its digits is 10080, while the sum is 30.

The square root of 21365724 is about 4622.3072160989. The cubic root of 21365724 is about 277.4848039727.

The spelling of 21365724 in words is "twenty-one million, three hundred sixty-five thousand, seven hundred twenty-four".