21379565 has 8 divisors (see below), whose sum is σ = 25785600. Its totient is φ = 17016912.

The previous prime is 21379559. The next prime is 21379571. The reversal of 21379565 is 56597312.

It is a happy number.

It is an interprime number because it is at equal distance from previous prime (21379559) and next prime (21379571).

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

It is a cyclic number.

It is not a de Polignac number, because 21379565 - 2⁴ = 21379549 is a prime.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 9749 + ... + 11738.

It is an arithmetic number, because the mean of its divisors is an integer number (3223200).

Almost surely, 2^21379565 is an apocalyptic number.

It is an amenable number.

21379565 is a deficient number, since it is larger than the sum of its proper divisors (4406035).

21379565 is a wasteful number, since it uses less digits than its factorization.

21379565 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 21691.

The product of its digits is 56700, while the sum is 38.

The square root of 21379565 is about 4623.8041697286. The cubic root of 21379565 is about 277.5447104866.

The spelling of 21379565 in words is "twenty-one million, three hundred seventy-nine thousand, five hundred sixty-five".