640577 has 12 divisors (see below), whose sum is σ = 790020. Its totient is φ = 516096.

The previous prime is 640531. The next prime is 640579. The reversal of 640577 is 775046.

It can be written as a sum of positive squares in 2 ways, for example, as 379456 + 261121 = 616^2 + 511^2 .

It is a de Polignac number, because none of the positive numbers 2^k-640577 is a prime.

It is not an unprimeable number, because it can be changed into a prime (640579) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 449 + ... + 1217.

It is an arithmetic number, because the mean of its divisors is an integer number (65835).

2⁶⁴⁰⁵⁷⁷ is an apocalyptic number.

It is an amenable number.

640577 is a deficient number, since it is larger than the sum of its proper divisors (149443).

640577 is a wasteful number, since it uses less digits than its factorization.

640577 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 800 (or 793 counting only the distinct ones).

The product of its (nonzero) digits is 5880, while the sum is 29.

The square root of 640577 is about 800.3605437551. The cubic root of 640577 is about 86.2032779226.

The spelling of 640577 in words is "six hundred forty thousand, five hundred seventy-seven".