81801937 has 4 divisors (see below), whose sum is σ = 93487936. Its totient is φ = 70115940.

The previous prime is 81801919. The next prime is 81801959. The reversal of 81801937 is 73910818.

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, and also an emirpimes, since its reverse is a distinct semiprime: 73910818 = 2 ⋅36955409.

It is a cyclic number.

It is not a de Polignac number, because 81801937 - 2⁷ = 81801809 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 81801896 and 81801905.

It is not an unprimeable number, because it can be changed into a prime (81801997) 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, 5842989 + ... + 5843002.

It is an arithmetic number, because the mean of its divisors is an integer number (23371984).

Almost surely, 2^81801937 is an apocalyptic number.

It is an amenable number.

81801937 is a deficient number, since it is larger than the sum of its proper divisors (11685999).

81801937 is a wasteful number, since it uses less digits than its factorization.

81801937 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 11685998.

The product of its (nonzero) digits is 12096, while the sum is 37.

The square root of 81801937 is about 9044.4423266446. The cubic root of 81801937 is about 434.0980775320.

The spelling of 81801937 in words is "eighty-one million, eight hundred one thousand, nine hundred thirty-seven".