81800887 has 4 divisors (see below), whose sum is σ = 93486736. Its totient is φ = 70115040.

The previous prime is 81800843. The next prime is 81800891. The reversal of 81800887 is 78800818.

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 81800887 - 2⁷ = 81800759 is a prime.

It is a super-2 number, since 2×81800887² = 13382770227973538, which contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81800287) 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, 5842914 + ... + 5842927.

It is an arithmetic number, because the mean of its divisors is an integer number (23371684).

Almost surely, 2^81800887 is an apocalyptic number.

81800887 is a deficient number, since it is larger than the sum of its proper divisors (11685849).

81800887 is a wasteful number, since it uses less digits than its factorization.

81800887 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 11685848.

The product of its (nonzero) digits is 28672, while the sum is 40.

The square root of 81800887 is about 9044.3842797617. The cubic root of 81800887 is about 434.0962201802.

The spelling of 81800887 in words is "eighty-one million, eight hundred thousand, eight hundred eighty-seven".