640555043 has 4 divisors (see below), whose sum is σ = 646774128. Its totient is φ = 634335960.

The previous prime is 640555031. The next prime is 640555061. The reversal of 640555043 is 340555046.

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

It is a cyclic number.

It is not a de Polignac number, because 640555043 - 2¹² = 640550947 is a prime.

It is a super-2 number, since 2×640555043² = 820621526225463698, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (640555093) 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, 3109388 + ... + 3109593.

It is an arithmetic number, because the mean of its divisors is an integer number (161693532).

Almost surely, 2^640555043 is an apocalyptic number.

640555043 is a deficient number, since it is larger than the sum of its proper divisors (6219085).

640555043 is a wasteful number, since it uses less digits than its factorization.

640555043 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 6219084.

The product of its (nonzero) digits is 36000, while the sum is 32.

The square root of 640555043 is about 25309.1889044276. The cubic root of 640555043 is about 862.0229298401.

The spelling of 640555043 in words is "six hundred forty million, five hundred fifty-five thousand, forty-three".