640812697 has 8 divisors (see below), whose sum is σ = 735829952. Its totient is φ = 546663600.

The previous prime is 640812673. The next prime is 640812713. The reversal of 640812697 is 796218046.

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

It is a de Polignac number, because none of the positive numbers 2^k-640812697 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (640812097) 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, 215454 + ... + 218407.

It is an arithmetic number, because the mean of its divisors is an integer number (91978744).

Almost surely, 2^640812697 is an apocalyptic number.

It is an amenable number.

640812697 is a deficient number, since it is larger than the sum of its proper divisors (95017255).

640812697 is a wasteful number, since it uses less digits than its factorization.

640812697 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 434079.

The product of its (nonzero) digits is 145152, while the sum is 43.

The square root of 640812697 is about 25314.2785202344. The cubic root of 640812697 is about 862.1384930982.

The spelling of 640812697 in words is "six hundred forty million, eight hundred twelve thousand, six hundred ninety-seven".