640192861 has 32 divisors (see below), whose sum is σ = 816076800. Its totient is φ = 487788480.

The previous prime is 640192849. The next prime is 640192867. The reversal of 640192861 is 168291046.

It is a happy number.

It is a cyclic number.

It is not a de Polignac number, because 640192861 - 2⁹ = 640192349 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 640192861.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (640192867) by changing a digit.

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 31 ways as a sum of consecutive naturals, for example, 696160 + ... + 697078.

It is an arithmetic number, because the mean of its divisors is an integer number (25502400).

Almost surely, 2^640192861 is an apocalyptic number.

It is an amenable number.

640192861 is a deficient number, since it is larger than the sum of its proper divisors (175883939).

640192861 is a wasteful number, since it uses less digits than its factorization.

640192861 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1129.

The product of its (nonzero) digits is 20736, while the sum is 37.

The square root of 640192861 is about 25302.0327444259. The cubic root of 640192861 is about 861.8604311583.

The spelling of 640192861 in words is "six hundred forty million, one hundred ninety-two thousand, eight hundred sixty-one".