81403873 has 4 divisors (see below), whose sum is σ = 81426708. Its totient is φ = 81381040.

The previous prime is 81403867. The next prime is 81403921. The reversal of 81403873 is 37830418.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 37830418 = 2 ⋅18915209.

It can be written as a sum of positive squares in 2 ways, for example, as 45319824 + 36084049 = 6732^2 + 6007^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-81403873 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (81403073) 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, 4786 + ... + 13627.

It is an arithmetic number, because the mean of its divisors is an integer number (20356677).

Almost surely, 2^81403873 is an apocalyptic number.

It is an amenable number.

81403873 is a deficient number, since it is larger than the sum of its proper divisors (22835).

81403873 is a wasteful number, since it uses less digits than its factorization.

81403873 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 22834.

The product of its (nonzero) digits is 16128, while the sum is 34.

The square root of 81403873 is about 9022.4094897095. The cubic root of 81403873 is about 433.3927972966.

The spelling of 81403873 in words is "eighty-one million, four hundred three thousand, eight hundred seventy-three".