81516157 has 4 divisors (see below), whose sum is σ = 82307680. Its totient is φ = 80724636.

The previous prime is 81516151. The next prime is 81516161. The reversal of 81516157 is 75161518.

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, and also an emirpimes, since its reverse is a distinct semiprime: 75161518 = 2 ⋅37580759.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-81516157 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 (81516151) 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, 395607 + ... + 395812.

It is an arithmetic number, because the mean of its divisors is an integer number (20576920).

Almost surely, 2^81516157 is an apocalyptic number.

It is an amenable number.

81516157 is a deficient number, since it is larger than the sum of its proper divisors (791523).

81516157 is a wasteful number, since it uses less digits than its factorization.

81516157 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 791522.

The product of its digits is 8400, while the sum is 34.

The square root of 81516157 is about 9028.6298517549. The cubic root of 81516157 is about 433.5919717659.

The spelling of 81516157 in words is "eighty-one million, five hundred sixteen thousand, one hundred fifty-seven".