21715705 has 32 divisors (see below), whose sum is σ = 29611008. Its totient is φ = 15153600.

The previous prime is 21715699. The next prime is 21715709. The reversal of 21715705 is 50751712.

It is not a de Polignac number, because 21715705 - 2³ = 21715697 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21715709) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 261594 + ... + 261676.

It is an arithmetic number, because the mean of its divisors is an integer number (925344).

Almost surely, 2^21715705 is an apocalyptic number.

It is an amenable number.

21715705 is a deficient number, since it is larger than the sum of its proper divisors (7895303).

21715705 is a wasteful number, since it uses less digits than its factorization.

21715705 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 237.

The product of its (nonzero) digits is 2450, while the sum is 28.

The square root of 21715705 is about 4660.0112660808. The cubic root of 21715705 is about 278.9917179147.

The spelling of 21715705 in words is "twenty-one million, seven hundred fifteen thousand, seven hundred five".