81751811 has 4 divisors (see below), whose sum is σ = 83294352. Its totient is φ = 80209272.

The previous prime is 81751799. The next prime is 81751829. The reversal of 81751811 is 11815718.

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

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-81751811 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (81751871) 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, 771191 + ... + 771296.

It is an arithmetic number, because the mean of its divisors is an integer number (20823588).

Almost surely, 2^81751811 is an apocalyptic number.

81751811 is a deficient number, since it is larger than the sum of its proper divisors (1542541).

81751811 is a wasteful number, since it uses less digits than its factorization.

81751811 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1542540.

The product of its digits is 2240, while the sum is 32.

The square root of 81751811 is about 9041.6708079868. The cubic root of 81751811 is about 434.0093915868.

The spelling of 81751811 in words is "eighty-one million, seven hundred fifty-one thousand, eight hundred eleven".