21870457 has 8 divisors (see below), whose sum is σ = 25059200. Its totient is φ = 18697824.

The previous prime is 21870451. The next prime is 21870461. The reversal of 21870457 is 75407812.

It is a happy number.

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

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21870457 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21870451) 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, 957 + ... + 6682.

It is an arithmetic number, because the mean of its divisors is an integer number (3132400).

Almost surely, 2^21870457 is an apocalyptic number.

It is an amenable number.

21870457 is a deficient number, since it is larger than the sum of its proper divisors (3188743).

21870457 is an equidigital number, since it uses as much as digits as its factorization.

21870457 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 8055.

The product of its (nonzero) digits is 15680, while the sum is 34.

The square root of 21870457 is about 4676.5860411202. The cubic root of 21870457 is about 279.6528734033.

The spelling of 21870457 in words is "twenty-one million, eight hundred seventy thousand, four hundred fifty-seven".