640877817 has 16 divisors (see below), whose sum is σ = 867240000. Its totient is φ = 420928704.

The previous prime is 640877813. The next prime is 640877821. The reversal of 640877817 is 718778046.

It is an interprime number because it is at equal distance from previous prime (640877813) and next prime (640877821).

It is not a de Polignac number, because 640877817 - 2² = 640877813 is a prime.

It is not an unprimeable number, because it can be changed into a prime (640877813) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 53059 + ... + 64007.

It is an arithmetic number, because the mean of its divisors is an integer number (54202500).

Almost surely, 2^640877817 is an apocalyptic number.

It is an amenable number.

640877817 is a deficient number, since it is larger than the sum of its proper divisors (226362183).

640877817 is a wasteful number, since it uses less digits than its factorization.

640877817 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 11240.

The product of its (nonzero) digits is 526848, while the sum is 48.

The square root of 640877817 is about 25315.5647181729. The cubic root of 640877817 is about 862.1676958888.

The spelling of 640877817 in words is "six hundred forty million, eight hundred seventy-seven thousand, eight hundred seventeen".