640714891 has 4 divisors (see below), whose sum is σ = 640773784. Its totient is φ = 640656000.

The previous prime is 640714889. The next prime is 640714897. The reversal of 640714891 is 198417046.

It is a semiprime because it is the product of two primes, and also a brilliant number, because the two primes have the same length, and also an emirpimes, since its reverse is a distinct semiprime: 198417046 = 2 ⋅99208523.

It is a cyclic number.

It is not a de Polignac number, because 640714891 - 2¹ = 640714889 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (640714897) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 7845 + ... + 36646.

It is an arithmetic number, because the mean of its divisors is an integer number (160193446).

Almost surely, 2^640714891 is an apocalyptic number.

640714891 is a deficient number, since it is larger than the sum of its proper divisors (58893).

640714891 is a wasteful number, since it uses less digits than its factorization.

640714891 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 58892.

The product of its (nonzero) digits is 48384, while the sum is 40.

The square root of 640714891 is about 25312.3466118809. The cubic root of 640714891 is about 862.0946286907.

The spelling of 640714891 in words is "six hundred forty million, seven hundred fourteen thousand, eight hundred ninety-one".