640661115 has 8 divisors (see below), whose sum is σ = 1025057808.
Its totient is φ = 341685920.
The previous prime is 640661093. The next prime is 640661129. The reversal of 640661115 is 511166046.
It is a sphenic number, since it is the product of 3 distinct primes.
It is not a de Polignac number, because 640661115 - 26 = 640661051 is a prime.
It is an unprimeable number.
It is a pernicious number, because its binary representation contains a prime number (19) of ones.
It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 21355356 + ... + 21355385.
It is an arithmetic number, because the mean of its divisors is an integer number (128132226).
Almost surely, 2640661115 is an apocalyptic number.
640661115 is a deficient number, since it is larger than the sum of its proper divisors (384396693).
640661115 is a wasteful number, since it uses less digits than its factorization.
640661115 is an odious number, because the sum of its binary digits is odd.
The sum of its prime factors is 42710749.
The product of its (nonzero) digits is 4320, while the sum is 30.
The square root of 640661115 is about 25311.2843411787.
The cubic root of 640661115 is about 862.0705091234.
The spelling of 640661115 in words is "six hundred forty million, six hundred sixty-one thousand, one hundred fifteen".