640434136477 has 4 divisors (see below), whose sum is σ = 641337429340. Its totient is φ = 639530843616.

The previous prime is 640434136457. The next prime is 640434136501. The reversal of 640434136477 is 774631434046.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 396510755481 + 243923380996 = 629691^2 + 493886^2 .

It is a cyclic number.

It is not a de Polignac number, because 640434136477 - 2³⁹ = 90678322589 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 640434136477.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (640434136417) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 451645368 + ... + 451646785.

It is an arithmetic number, because the mean of its divisors is an integer number (160334357335).

Almost surely, 2^640434136477 is an apocalyptic number.

It is an amenable number.

640434136477 is a deficient number, since it is larger than the sum of its proper divisors (903292863).

640434136477 is an equidigital number, since it uses as much as digits as its factorization.

640434136477 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 903292862.

The product of its (nonzero) digits is 4064256, while the sum is 49.

The spelling of 640434136477 in words is "six hundred forty billion, four hundred thirty-four million, one hundred thirty-six thousand, four hundred seventy-seven".