640251607 has 8 divisors (see below), whose sum is σ = 686666160. Its totient is φ = 595108800.

The previous prime is 640251581. The next prime is 640251617. The reversal of 640251607 is 706152046.

It is a happy number.

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

It is a cyclic number.

It is not a de Polignac number, because 640251607 - 2²³ = 631862999 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (640251617) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 316894 + ... + 318907.

It is an arithmetic number, because the mean of its divisors is an integer number (85833270).

Almost surely, 2^640251607 is an apocalyptic number.

640251607 is a deficient number, since it is larger than the sum of its proper divisors (46414553).

640251607 is a wasteful number, since it uses less digits than its factorization.

640251607 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 635873.

The product of its (nonzero) digits is 10080, while the sum is 31.

The square root of 640251607 is about 25303.1936126648. The cubic root of 640251607 is about 861.8867926437.

The spelling of 640251607 in words is "six hundred forty million, two hundred fifty-one thousand, six hundred seven".