20649865 has 8 divisors (see below), whose sum is σ = 26084160. Its totient is φ = 15650352.

The previous prime is 20649859. The next prime is 20649887. The reversal of 20649865 is 56894602.

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 20649865 - 2³ = 20649857 is a prime.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 108589 + ... + 108778.

It is an arithmetic number, because the mean of its divisors is an integer number (3260520).

Almost surely, 2^20649865 is an apocalyptic number.

It is an amenable number.

20649865 is a deficient number, since it is larger than the sum of its proper divisors (5434295).

20649865 is a wasteful number, since it uses less digits than its factorization.

20649865 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 217391.

The product of its (nonzero) digits is 103680, while the sum is 40.

The square root of 20649865 is about 4544.2122529653. The cubic root of 20649865 is about 274.3504891944.

The spelling of 20649865 in words is "twenty million, six hundred forty-nine thousand, eight hundred sixty-five".