640891611 has 12 divisors (see below), whose sum is σ = 930122440. Its totient is φ = 425234880.

The previous prime is 640891607. The next prime is 640891627. The reversal of 640891611 is 116198046.

It is a happy number.

640891611 is a `hidden beast` number, since 640 + 8 + 9 + 1 + 6 + 1 + 1 = 666.

It is not a de Polignac number, because 640891611 - 2² = 640891607 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (640891631) 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 11 ways as a sum of consecutive naturals, for example, 166846 + ... + 170643.

Almost surely, 2^640891611 is an apocalyptic number.

640891611 is a deficient number, since it is larger than the sum of its proper divisors (289230829).

640891611 is a wasteful number, since it uses less digits than its factorization.

640891611 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 337706 (or 337703 counting only the distinct ones).

The product of its (nonzero) digits is 10368, while the sum is 36.

The square root of 640891611 is about 25315.8371577951. The cubic root of 640891611 is about 862.1738814963.

The spelling of 640891611 in words is "six hundred forty million, eight hundred ninety-one thousand, six hundred eleven".