21356457 has 8 divisors (see below), whose sum is σ = 28517760. Its totient is φ = 14216400.

The previous prime is 21356453. The next prime is 21356459. The reversal of 21356457 is 75465312.

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

It is not a de Polignac number, because 21356457 - 2² = 21356453 is a prime.

It is not an unprimeable number, because it can be changed into a prime (21356453) 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, 2794 + ... + 7107.

It is an arithmetic number, because the mean of its divisors is an integer number (3564720).

Almost surely, 2^21356457 is an apocalyptic number.

It is an amenable number.

21356457 is a deficient number, since it is larger than the sum of its proper divisors (7161303).

21356457 is an equidigital number, since it uses as much as digits as its factorization.

21356457 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 10623.

The product of its digits is 25200, while the sum is 33.

The square root of 21356457 is about 4621.3046859085. The cubic root of 21356457 is about 277.4446801503. Note that the first 3 decimals are identical.

The spelling of 21356457 in words is "twenty-one million, three hundred fifty-six thousand, four hundred fifty-seven".