640971554 has 8 divisors (see below), whose sum is σ = 961566060. Its totient is φ = 320449536.

The previous prime is 640971533. The next prime is 640971589. The reversal of 640971554 is 455179046.

It can be written as a sum of positive squares in 2 ways, for example, as 560600329 + 80371225 = 23677^2 + 8965^2 .

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

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 20162 + ... + 41090.

Almost surely, 2^640971554 is an apocalyptic number.

640971554 is a deficient number, since it is larger than the sum of its proper divisors (320594506).

640971554 is a wasteful number, since it uses less digits than its factorization.

640971554 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 36244.

The product of its (nonzero) digits is 151200, while the sum is 41.

The square root of 640971554 is about 25317.4160213873. The cubic root of 640971554 is about 862.2097283799.

The spelling of 640971554 in words is "six hundred forty million, nine hundred seventy-one thousand, five hundred fifty-four".