640376977 has 2 divisors, whose sum is σ = 640376978. Its totient is φ = 640376976.

The previous prime is 640376953. The next prime is 640376981. The reversal of 640376977 is 779673046.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 404170816 + 236206161 = 20104^2 + 15369^2 .

It is a cyclic number.

It is not a de Polignac number, because 640376977 - 2¹¹ = 640374929 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 640376977.

It is not a weakly prime, because it can be changed into another prime (640376777) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 320188488 + 320188489.

It is an arithmetic number, because the mean of its divisors is an integer number (320188489).

Almost surely, 2^640376977 is an apocalyptic number.

It is an amenable number.

640376977 is a deficient number, since it is larger than the sum of its proper divisors (1).

640376977 is an equidigital number, since it uses as much as digits as its factorization.

640376977 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 1333584, while the sum is 49.

The square root of 640376977 is about 25305.6708466699. The cubic root of 640376977 is about 861.9430453700.

The spelling of 640376977 in words is "six hundred forty million, three hundred seventy-six thousand, nine hundred seventy-seven".