640081077 has 4 divisors (see below), whose sum is σ = 853441440. Its totient is φ = 426720716.

The previous prime is 640081073. The next prime is 640081097. The reversal of 640081077 is 770180046.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 640081077 - 2² = 640081073 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (640081073) 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, 106680177 + ... + 106680182.

It is an arithmetic number, because the mean of its divisors is an integer number (213360360).

Almost surely, 2^640081077 is an apocalyptic number.

It is an amenable number.

640081077 is a deficient number, since it is larger than the sum of its proper divisors (213360363).

640081077 is a wasteful number, since it uses less digits than its factorization.

640081077 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 213360362.

The product of its (nonzero) digits is 9408, while the sum is 33.

The square root of 640081077 is about 25299.8236555119. The cubic root of 640081077 is about 861.8102651223.

The spelling of 640081077 in words is "six hundred forty million, eighty-one thousand, seventy-seven".