8261581257 has 16 divisors (see below), whose sum is σ = 12259241280. Its totient is φ = 5498783136.

The previous prime is 8261581253. The next prime is 8261581283. The reversal of 8261581257 is 7521851628.

8261581257 is a `hidden beast` number, since 8 + 2 + 61 + 581 + 2 + 5 + 7 = 666.

It is not a de Polignac number, because 8261581257 - 2² = 8261581253 is a prime.

It is not an unprimeable number, because it can be changed into a prime (8261581253) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 231303 + ... + 264620.

It is an arithmetic number, because the mean of its divisors is an integer number (766202580).

Almost surely, 2^8261581257 is an apocalyptic number.

It is an amenable number.

8261581257 is a deficient number, since it is larger than the sum of its proper divisors (3997660023).

8261581257 is a wasteful number, since it uses less digits than its factorization.

8261581257 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 496549 (or 496543 counting only the distinct ones).

The product of its digits is 268800, while the sum is 45.

The square root of 8261581257 is about 90893.2409863352. The cubic root of 8261581257 is about 2021.5650760889.

The spelling of 8261581257 in words is "eight billion, two hundred sixty-one million, five hundred eighty-one thousand, two hundred fifty-seven".