21715745 has 8 divisors (see below), whose sum is σ = 26196480. Its totient is φ = 17280880.

The previous prime is 21715741. The next prime is 21715747. The reversal of 21715745 is 54751712.

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 21715745 - 2² = 21715741 is a prime.

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (21715741) 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, 10415 + ... + 12324.

It is an arithmetic number, because the mean of its divisors is an integer number (3274560).

Almost surely, 2^21715745 is an apocalyptic number.

It is an amenable number.

21715745 is a deficient number, since it is larger than the sum of its proper divisors (4480735).

21715745 is a wasteful number, since it uses less digits than its factorization.

21715745 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 22935.

The product of its digits is 9800, while the sum is 32.

The square root of 21715745 is about 4660.0155579139. The cubic root of 21715745 is about 278.9918892141.

The spelling of 21715745 in words is "twenty-one million, seven hundred fifteen thousand, seven hundred forty-five".