81948757 has 16 divisors (see below), whose sum is σ = 91054080. Its totient is φ = 73134000.

The previous prime is 81948749. The next prime is 81948781. The reversal of 81948757 is 75784918.

It is a cyclic number.

It is not a de Polignac number, because 81948757 - 2³ = 81948749 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 81948757.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81948157) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 170844 + ... + 171322.

It is an arithmetic number, because the mean of its divisors is an integer number (5690880).

Almost surely, 2^81948757 is an apocalyptic number.

It is an amenable number.

81948757 is a deficient number, since it is larger than the sum of its proper divisors (9105323).

81948757 is a wasteful number, since it uses less digits than its factorization.

81948757 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 744.

The product of its digits is 564480, while the sum is 49.

The square root of 81948757 is about 9052.5552746172. Note that the first 3 decimals coincide. The cubic root of 81948757 is about 434.3576320506.

The spelling of 81948757 in words is "eighty-one million, nine hundred forty-eight thousand, seven hundred fifty-seven".