81800771 has 4 divisors (see below), whose sum is σ = 88093152. Its totient is φ = 75508392.

The previous prime is 81800759. The next prime is 81800791. The reversal of 81800771 is 17700818.

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 81800771 - 2¹⁴ = 81784387 is a prime.

It is a super-2 number, since 2×81800771² = 13382732272388882, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (81800711) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 3146171 + ... + 3146196.

It is an arithmetic number, because the mean of its divisors is an integer number (22023288).

Almost surely, 2^81800771 is an apocalyptic number.

81800771 is a deficient number, since it is larger than the sum of its proper divisors (6292381).

81800771 is a wasteful number, since it uses less digits than its factorization.

81800771 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 6292380.

The product of its (nonzero) digits is 3136, while the sum is 32.

The square root of 81800771 is about 9044.3778669403. The cubic root of 81800771 is about 434.0960149860.

The spelling of 81800771 in words is "eighty-one million, eight hundred thousand, seven hundred seventy-one".