640703987 has 8 divisors (see below), whose sum is σ = 798799872. Its totient is φ = 499249800.

The previous prime is 640703977. The next prime is 640703993. The reversal of 640703987 is 789307046.

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

It is not a de Polignac number, because 640703987 - 2¹⁴ = 640687603 is a prime.

It is a super-3 number, since 3×640703987³ (a number of 27 digits) contains 333 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (640703957) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 4160339 + ... + 4160492.

It is an arithmetic number, because the mean of its divisors is an integer number (99849984).

Almost surely, 2^640703987 is an apocalyptic number.

640703987 is a deficient number, since it is larger than the sum of its proper divisors (158095885).

640703987 is a wasteful number, since it uses less digits than its factorization.

640703987 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 8320849.

The product of its (nonzero) digits is 254016, while the sum is 44.

The square root of 640703987 is about 25312.1312220050. The cubic root of 640703987 is about 862.0897381467.

The spelling of 640703987 in words is "six hundred forty million, seven hundred three thousand, nine hundred eighty-seven".