640541677 has 2 divisors, whose sum is σ = 640541678. Its totient is φ = 640541676.

The previous prime is 640541621. The next prime is 640541683. The reversal of 640541677 is 776145046.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 360012676 + 280529001 = 18974^2 + 16749^2 .

It is a cyclic number.

It is not a de Polignac number, because 640541677 - 2²³ = 632153069 is a prime.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (640541617) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 320270838 + 320270839.

It is an arithmetic number, because the mean of its divisors is an integer number (320270839).

Almost surely, 2^640541677 is an apocalyptic number.

It is an amenable number.

640541677 is a deficient number, since it is larger than the sum of its proper divisors (1).

640541677 is an equidigital number, since it uses as much as digits as its factorization.

640541677 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 141120, while the sum is 40.

The square root of 640541677 is about 25308.9248487564. The cubic root of 640541677 is about 862.0169340615.

The spelling of 640541677 in words is "six hundred forty million, five hundred forty-one thousand, six hundred seventy-seven".