81800823 has 16 divisors (see below), whose sum is σ = 117705056. Its totient is φ = 50232960.

The previous prime is 81800819. The next prime is 81800843. The reversal of 81800823 is 32800818.

It is not a de Polignac number, because 81800823 - 2² = 81800819 is a prime.

It is a super-3 number, since 3×81800823³ (a number of 25 digits) contains 333 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81800843) 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, 19161 + ... + 23037.

It is an arithmetic number, because the mean of its divisors is an integer number (7356566).

Almost surely, 2^81800823 is an apocalyptic number.

81800823 is a deficient number, since it is larger than the sum of its proper divisors (35904233).

81800823 is a wasteful number, since it uses less digits than its factorization.

81800823 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4434.

The product of its (nonzero) digits is 3072, while the sum is 30.

The square root of 81800823 is about 9044.3807416539. The cubic root of 81800823 is about 434.0961069696.

The spelling of 81800823 in words is "eighty-one million, eight hundred thousand, eight hundred twenty-three".