81192761 has 4 divisors (see below), whose sum is σ = 87438372. Its totient is φ = 74947152.

The previous prime is 81192701. The next prime is 81192773. The reversal of 81192761 is 16729118.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 42055225 + 39137536 = 6485^2 + 6256^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-81192761 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (81192701) 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, 3122786 + ... + 3122811.

It is an arithmetic number, because the mean of its divisors is an integer number (21859593).

Almost surely, 2^81192761 is an apocalyptic number.

It is an amenable number.

81192761 is a deficient number, since it is larger than the sum of its proper divisors (6245611).

81192761 is a wasteful number, since it uses less digits than its factorization.

81192761 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 6245610.

The product of its digits is 6048, while the sum is 35.

The square root of 81192761 is about 9010.7025808202. The cubic root of 81192761 is about 433.0178207565.

The spelling of 81192761 in words is "eighty-one million, one hundred ninety-two thousand, seven hundred sixty-one".