81130557 has 4 divisors (see below), whose sum is σ = 108174080. Its totient is φ = 54087036.

The previous prime is 81130541. The next prime is 81130561. The reversal of 81130557 is 75503118.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is not a de Polignac number, because 81130557 - 2⁴ = 81130541 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81130457) 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, 13521757 + ... + 13521762.

It is an arithmetic number, because the mean of its divisors is an integer number (27043520).

Almost surely, 2^81130557 is an apocalyptic number.

It is an amenable number.

81130557 is a deficient number, since it is larger than the sum of its proper divisors (27043523).

81130557 is a wasteful number, since it uses less digits than its factorization.

81130557 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 27043522.

The product of its (nonzero) digits is 4200, while the sum is 30.

The square root of 81130557 is about 9007.2502463293. The cubic root of 81130557 is about 432.9072102301.

The spelling of 81130557 in words is "eighty-one million, one hundred thirty thousand, five hundred fifty-seven".