81157537 has 4 divisors (see below), whose sum is σ = 81655600. Its totient is φ = 80659476.

The previous prime is 81157529. The next prime is 81157543. The reversal of 81157537 is 73575118.

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 a cyclic number.

It is not a de Polignac number, because 81157537 - 2³ = 81157529 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 81157496 and 81157505.

It is not an unprimeable number, because it can be changed into a prime (81152537) 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, 248787 + ... + 249112.

It is an arithmetic number, because the mean of its divisors is an integer number (20413900).

Almost surely, 2^81157537 is an apocalyptic number.

It is an amenable number.

81157537 is a deficient number, since it is larger than the sum of its proper divisors (498063).

81157537 is a wasteful number, since it uses less digits than its factorization.

81157537 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 498062.

The product of its digits is 29400, while the sum is 37.

The square root of 81157537 is about 9008.7478042179. The cubic root of 81157537 is about 432.9551927350.

The spelling of 81157537 in words is "eighty-one million, one hundred fifty-seven thousand, five hundred thirty-seven".