640235767 has 2 divisors, whose sum is σ = 640235768. Its totient is φ = 640235766.

The previous prime is 640235737. The next prime is 640235773. The reversal of 640235767 is 767532046.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 640235767 - 2²³ = 631847159 is a prime.

It is a super-3 number, since 3×640235767³ (a number of 27 digits) contains 333 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (640235737) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 320117883 + 320117884.

It is an arithmetic number, because the mean of its divisors is an integer number (320117884).

Almost surely, 2^640235767 is an apocalyptic number.

640235767 is a deficient number, since it is larger than the sum of its proper divisors (1).

640235767 is an equidigital number, since it uses as much as digits as its factorization.

640235767 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 211680, while the sum is 40.

The square root of 640235767 is about 25302.8806067610. The cubic root of 640235767 is about 861.8796848134.

The spelling of 640235767 in words is "six hundred forty million, two hundred thirty-five thousand, seven hundred sixty-seven".