640554879 has 4 divisors (see below), whose sum is σ = 854073176. Its totient is φ = 427036584.

The previous prime is 640554877. The next prime is 640554881. The reversal of 640554879 is 978455046.

It is a semiprime because it is the product of two primes.

It is an interprime number because it is at equal distance from previous prime (640554877) and next prime (640554881).

It is not a de Polignac number, because 640554879 - 2¹ = 640554877 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (640554877) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 106759144 + ... + 106759149.

It is an arithmetic number, because the mean of its divisors is an integer number (213518294).

Almost surely, 2^640554879 is an apocalyptic number.

640554879 is a deficient number, since it is larger than the sum of its proper divisors (213518297).

640554879 is a wasteful number, since it uses less digits than its factorization.

640554879 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 213518296.

The product of its (nonzero) digits is 1209600, while the sum is 48.

The square root of 640554879 is about 25309.1856644974. The cubic root of 640554879 is about 862.0228562728.

The spelling of 640554879 in words is "six hundred forty million, five hundred fifty-four thousand, eight hundred seventy-nine".