640645461 has 12 divisors (see below), whose sum is σ = 926460288. Its totient is φ = 426596904.

The previous prime is 640645457. The next prime is 640645463. The reversal of 640645461 is 164546046.

640645461 is a `hidden beast` number, since 6 + 4 + 0 + 645 + 4 + 6 + 1 = 666.

It is not a de Polignac number, because 640645461 - 2² = 640645457 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (640645463) 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, 33475 + ... + 49008.

It is an arithmetic number, because the mean of its divisors is an integer number (77205024).

Almost surely, 2^640645461 is an apocalyptic number.

It is an amenable number.

640645461 is a deficient number, since it is larger than the sum of its proper divisors (285814827).

640645461 is a wasteful number, since it uses less digits than its factorization.

640645461 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 83352 (or 83349 counting only the distinct ones).

The product of its (nonzero) digits is 69120, while the sum is 36.

The square root of 640645461 is about 25310.9751096239. The cubic root of 640645461 is about 862.0634877506.

The spelling of 640645461 in words is "six hundred forty million, six hundred forty-five thousand, four hundred sixty-one".