21360657 has 4 divisors (see below), whose sum is σ = 28480880. Its totient is φ = 14240436.

The previous prime is 21360649. The next prime is 21360659. The reversal of 21360657 is 75606312.

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 not a de Polignac number, because 21360657 - 2³ = 21360649 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21360659) 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, 3560107 + ... + 3560112.

It is an arithmetic number, because the mean of its divisors is an integer number (7120220).

Almost surely, 2^21360657 is an apocalyptic number.

It is an amenable number.

21360657 is a deficient number, since it is larger than the sum of its proper divisors (7120223).

21360657 is an equidigital number, since it uses as much as digits as its factorization.

21360657 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 7120222.

The product of its (nonzero) digits is 7560, while the sum is 30.

The square root of 21360657 is about 4621.7590806964. The cubic root of 21360657 is about 277.4628665514.

Adding to 21360657 its reverse (75606312), we get a palindrome (96966969).

The spelling of 21360657 in words is "twenty-one million, three hundred sixty thousand, six hundred fifty-seven".