21580865 has 8 divisors (see below), whose sum is σ = 27260160. Its totient is φ = 16355952.

The previous prime is 21580859. The next prime is 21580873. The reversal of 21580865 is 56808512.

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 not a de Polignac number, because 21580865 - 2⁸ = 21580609 is a prime.

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, 113489 + ... + 113678.

It is an arithmetic number, because the mean of its divisors is an integer number (3407520).

Almost surely, 2^21580865 is an apocalyptic number.

It is an amenable number.

21580865 is a deficient number, since it is larger than the sum of its proper divisors (5679295).

21580865 is a wasteful number, since it uses less digits than its factorization.

21580865 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 227191.

The product of its (nonzero) digits is 19200, while the sum is 35.

The square root of 21580865 is about 4645.5209610979. The cubic root of 21580865 is about 278.4130679406.

The spelling of 21580865 in words is "twenty-one million, five hundred eighty thousand, eight hundred sixty-five".