81133757 has 4 divisors (see below), whose sum is σ = 81186720. Its totient is φ = 81080796.

The previous prime is 81133747. The next prime is 81133763. The reversal of 81133757 is 75733118.

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 81133757 - 2⁸ = 81133501 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 (81133747) 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, 24113 + ... + 27270.

It is an arithmetic number, because the mean of its divisors is an integer number (20296680).

Almost surely, 2^81133757 is an apocalyptic number.

It is an amenable number.

81133757 is a deficient number, since it is larger than the sum of its proper divisors (52963).

81133757 is a wasteful number, since it uses less digits than its factorization.

81133757 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 52962.

The product of its digits is 17640, while the sum is 35.

The square root of 81133757 is about 9007.4278792561. The cubic root of 81133757 is about 432.9129018170.

The spelling of 81133757 in words is "eighty-one million, one hundred thirty-three thousand, seven hundred fifty-seven".