21566065 has 8 divisors (see below), whose sum is σ = 27004608. Its totient is φ = 16502640.

The previous prime is 21566063. The next prime is 21566087. The reversal of 21566065 is 56066512.

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

It is not a de Polignac number, because 21566065 - 2¹ = 21566063 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21566063) 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, 93651 + ... + 93880.

It is an arithmetic number, because the mean of its divisors is an integer number (3375576).

Almost surely, 2^21566065 is an apocalyptic number.

It is an amenable number.

21566065 is a deficient number, since it is larger than the sum of its proper divisors (5438543).

21566065 is a wasteful number, since it uses less digits than its factorization.

21566065 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 187559.

The product of its (nonzero) digits is 10800, while the sum is 31.

The square root of 21566065 is about 4643.9277556827. The cubic root of 21566065 is about 278.3494088348.

The spelling of 21566065 in words is "twenty-one million, five hundred sixty-six thousand, sixty-five".