640020677 has 2 divisors, whose sum is σ = 640020678. Its totient is φ = 640020676.

The previous prime is 640020673. The next prime is 640020751. The reversal of 640020677 is 776020046.

It is a happy number.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 637360516 + 2660161 = 25246^2 + 1631^2 .

It is a cyclic number.

It is not a de Polignac number, because 640020677 - 2² = 640020673 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 (640020673) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 320010338 + 320010339.

It is an arithmetic number, because the mean of its divisors is an integer number (320010339).

Almost surely, 2^640020677 is an apocalyptic number.

It is an amenable number.

640020677 is a deficient number, since it is larger than the sum of its proper divisors (1).

640020677 is an equidigital number, since it uses as much as digits as its factorization.

640020677 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 14112, while the sum is 32.

The square root of 640020677 is about 25298.6299431412. The cubic root of 640020677 is about 861.7831565891.

The spelling of 640020677 in words is "six hundred forty million, twenty thousand, six hundred seventy-seven".