21715417 has 4 divisors (see below), whose sum is σ = 21764880. Its totient is φ = 21665956.

The previous prime is 21715361. The next prime is 21715433. The reversal of 21715417 is 71451712.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21715417 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21715217) 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, 24067 + ... + 24952.

It is an arithmetic number, because the mean of its divisors is an integer number (5441220).

Almost surely, 2^21715417 is an apocalyptic number.

It is an amenable number.

21715417 is a deficient number, since it is larger than the sum of its proper divisors (49463).

21715417 is an equidigital number, since it uses as much as digits as its factorization.

21715417 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 49462.

The product of its digits is 1960, while the sum is 28.

The square root of 21715417 is about 4659.9803647655. The cubic root of 21715417 is about 278.9904845528.

The spelling of 21715417 in words is "twenty-one million, seven hundred fifteen thousand, four hundred seventeen".