640677867 has 4 divisors (see below), whose sum is σ = 854237160. Its totient is φ = 427118576.

The previous prime is 640677859. The next prime is 640677871. The reversal of 640677867 is 768776046.

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

It is a cyclic number.

It is not a de Polignac number, because 640677867 - 2³ = 640677859 is a prime.

It is not an unprimeable number, because it can be changed into a prime (640677847) 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, 106779642 + ... + 106779647.

It is an arithmetic number, because the mean of its divisors is an integer number (213559290).

Almost surely, 2^640677867 is an apocalyptic number.

640677867 is a deficient number, since it is larger than the sum of its proper divisors (213559293).

640677867 is a wasteful number, since it uses less digits than its factorization.

640677867 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 213559292.

The product of its (nonzero) digits is 2370816, while the sum is 51.

The square root of 640677867 is about 25311.6152586120. The cubic root of 640677867 is about 862.0780228614.

The spelling of 640677867 in words is "six hundred forty million, six hundred seventy-seven thousand, eight hundred sixty-seven".