640212557 has 2 divisors, whose sum is σ = 640212558. Its totient is φ = 640212556.

The previous prime is 640212541. The next prime is 640212563. The reversal of 640212557 is 755212046.

640212557 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 320911396 + 319301161 = 17914^2 + 17869^2 .

It is a cyclic number.

It is not a de Polignac number, because 640212557 - 2⁴ = 640212541 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (640212257) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 320106278 + 320106279.

It is an arithmetic number, because the mean of its divisors is an integer number (320106279).

Almost surely, 2^640212557 is an apocalyptic number.

It is an amenable number.

640212557 is a deficient number, since it is larger than the sum of its proper divisors (1).

640212557 is an equidigital number, since it uses as much as digits as its factorization.

640212557 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 16800, while the sum is 32.

The square root of 640212557 is about 25302.4219591722. The cubic root of 640212557 is about 861.8692696558.

The spelling of 640212557 in words is "six hundred forty million, two hundred twelve thousand, five hundred fifty-seven".