581981157 has 6 divisors (see below), whose sum is σ = 840639462. Its totient is φ = 387987432.

The previous prime is 581981137. The next prime is 581981159. The reversal of 581981157 is 751189185.

581981157 is a `hidden beast` number, since 581 + 9 + 8 + 11 + 57 = 666.

It can be written as a sum of positive squares in only one way, i.e., 429359841 + 152621316 = 20721^2 + 12354^2 .

It is not a de Polignac number, because 581981157 - 2⁶ = 581981093 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (581981159) by changing a digit.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 32332278 + ... + 32332295.

It is an arithmetic number, because the mean of its divisors is an integer number (140106577).

Almost surely, 2^581981157 is an apocalyptic number.

It is an amenable number.

581981157 is a deficient number, since it is larger than the sum of its proper divisors (258658305).

581981157 is a wasteful number, since it uses less digits than its factorization.

581981157 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 64664579 (or 64664576 counting only the distinct ones).

The product of its digits is 100800, while the sum is 45.

The square root of 581981157 is about 24124.2856267289. The cubic root of 581981157 is about 834.9035503594.

The spelling of 581981157 in words is "five hundred eighty-one million, nine hundred eighty-one thousand, one hundred fifty-seven".