640877815 has 16 divisors (see below), whose sum is σ = 842374080. Its totient is φ = 465902080.

The previous prime is 640877813. The next prime is 640877821. The reversal of 640877815 is 518778046.

640877815 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is not a de Polignac number, because 640877815 - 2¹ = 640877813 is a prime.

It is a congruent number.

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, 127531 + ... + 132460.

It is an arithmetic number, because the mean of its divisors is an integer number (52648380).

Almost surely, 2^640877815 is an apocalyptic number.

640877815 is a deficient number, since it is larger than the sum of its proper divisors (201496265).

640877815 is a wasteful number, since it uses less digits than its factorization.

640877815 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 260042.

The product of its (nonzero) digits is 376320, while the sum is 46.

The square root of 640877815 is about 25315.5646786715. The cubic root of 640877815 is about 862.1676949920.

The spelling of 640877815 in words is "six hundred forty million, eight hundred seventy-seven thousand, eight hundred fifteen".