20640651 has 8 divisors (see below), whose sum is σ = 27542160. Its totient is φ = 13749792.

The previous prime is 20640647. The next prime is 20640667. The reversal of 20640651 is 15604602.

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

It is not a de Polignac number, because 20640651 - 2² = 20640647 is a prime.

It is a Smith number, since the sum of its digits (24) coincides with the sum of the digits of its prime factors. Since it is squarefree, it is also a hoax number.

It is not an unprimeable number, because it can be changed into a prime (20640751) 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, 5085 + ... + 8193.

It is an arithmetic number, because the mean of its divisors is an integer number (3442770).

Almost surely, 2^20640651 is an apocalyptic number.

20640651 is a deficient number, since it is larger than the sum of its proper divisors (6901509).

20640651 is a wasteful number, since it uses less digits than its factorization.

20640651 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 5325.

The product of its (nonzero) digits is 1440, while the sum is 24.

The square root of 20640651 is about 4543.1983227678. The cubic root of 20640651 is about 274.3096779271.

The spelling of 20640651 in words is "twenty million, six hundred forty thousand, six hundred fifty-one".