81168751 has 4 divisors (see below), whose sum is σ = 81972504. Its totient is φ = 80365000.

The previous prime is 81168749. The next prime is 81168827. The reversal of 81168751 is 15786118.

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

It is a cyclic number.

It is not a de Polignac number, because 81168751 - 2¹ = 81168749 is a prime.

It is a super-2 number, since 2×81168751² = 13176732277800002, which contains 22 as substring.

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 81168751.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81168721) 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, 401725 + ... + 401926.

It is an arithmetic number, because the mean of its divisors is an integer number (20493126).

Almost surely, 2^81168751 is an apocalyptic number.

81168751 is a deficient number, since it is larger than the sum of its proper divisors (803753).

81168751 is a wasteful number, since it uses less digits than its factorization.

81168751 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 803752.

The product of its digits is 13440, while the sum is 37.

The square root of 81168751 is about 9009.3701777649. The cubic root of 81168751 is about 432.9751331132.

The spelling of 81168751 in words is "eighty-one million, one hundred sixty-eight thousand, seven hundred fifty-one".