81800149 has 4 divisors (see below), whose sum is σ = 86105440. Its totient is φ = 77494860.

The previous prime is 81800119. The next prime is 81800221. The reversal of 81800149 is 94100818.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-81800149 is a prime.

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 81800149.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81800119) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 2152617 + ... + 2152654.

It is an arithmetic number, because the mean of its divisors is an integer number (21526360).

Almost surely, 2^81800149 is an apocalyptic number.

It is an amenable number.

81800149 is a deficient number, since it is larger than the sum of its proper divisors (4305291).

81800149 is a wasteful number, since it uses less digits than its factorization.

81800149 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4305290.

The product of its (nonzero) digits is 2304, while the sum is 31.

The square root of 81800149 is about 9044.3434808725. The cubic root of 81800149 is about 434.0949147177.

The spelling of 81800149 in words is "eighty-one million, eight hundred thousand, one hundred forty-nine".