640185787 has 2 divisors, whose sum is σ = 640185788. Its totient is φ = 640185786.

The previous prime is 640185769. The next prime is 640185809. The reversal of 640185787 is 787581046.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 640185787 - 2⁷ = 640185659 is a prime.

It is not a weakly prime, because it can be changed into another prime (640186787) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 320092893 + 320092894.

It is an arithmetic number, because the mean of its divisors is an integer number (320092894).

Almost surely, 2^640185787 is an apocalyptic number.

640185787 is a deficient number, since it is larger than the sum of its proper divisors (1).

640185787 is an equidigital number, since it uses as much as digits as its factorization.

640185787 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 376320, while the sum is 46.

The square root of 640185787 is about 25301.8929528998. The cubic root of 640185787 is about 861.8572566862.

The spelling of 640185787 in words is "six hundred forty million, one hundred eighty-five thousand, seven hundred eighty-seven".