641557915 has 4 divisors (see below), whose sum is σ = 769869504. Its totient is φ = 513246328.

The previous prime is 641557909. The next prime is 641557919. The reversal of 641557915 is 519755146.

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 641557915 - 2³ = 641557907 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (641557919) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 64155787 + ... + 64155796.

It is an arithmetic number, because the mean of its divisors is an integer number (192467376).

Almost surely, 2^641557915 is an apocalyptic number.

641557915 is a deficient number, since it is larger than the sum of its proper divisors (128311589).

641557915 is a wasteful number, since it uses less digits than its factorization.

641557915 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 128311588.

The product of its digits is 189000, while the sum is 43.

The square root of 641557915 is about 25328.9935646879. The cubic root of 641557915 is about 862.4725648348.

The spelling of 641557915 in words is "six hundred forty-one million, five hundred fifty-seven thousand, nine hundred fifteen".