21715072 has 16 divisors (see below), whose sum is σ = 43260750. Its totient is φ = 10857472.

The previous prime is 21715063. The next prime is 21715087. The reversal of 21715072 is 27051712.

It is a happy number.

It can be written as a sum of positive squares in only one way, i.e., 19571776 + 2143296 = 4424^2 + 1464^2 .

It is a tau number, because it is divible by the number of its divisors (16).

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 84697 + ... + 84952.

Almost surely, 2^21715072 is an apocalyptic number.

It is an amenable number.

21715072 is a deficient number, since it is larger than the sum of its proper divisors (21545678).

21715072 is an equidigital number, since it uses as much as digits as its factorization.

21715072 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 169663 (or 169651 counting only the distinct ones).

The product of its (nonzero) digits is 980, while the sum is 25.

The square root of 21715072 is about 4659.9433472951. The cubic root of 21715072 is about 278.9890070736.

Adding to 21715072 its reverse (27051712), we get a palindrome (48766784).

The spelling of 21715072 in words is "twenty-one million, seven hundred fifteen thousand, seventy-two".