81087173 has 4 divisors (see below), whose sum is σ = 82812480. Its totient is φ = 79361868.

The previous prime is 81087157. The next prime is 81087187. The reversal of 81087173 is 37178018.

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 not a de Polignac number, because 81087173 - 2⁴ = 81087157 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81087133) 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, 862583 + ... + 862676.

It is an arithmetic number, because the mean of its divisors is an integer number (20703120).

Almost surely, 2^81087173 is an apocalyptic number.

It is an amenable number.

81087173 is a deficient number, since it is larger than the sum of its proper divisors (1725307).

81087173 is a wasteful number, since it uses less digits than its factorization.

81087173 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1725306.

The product of its (nonzero) digits is 9408, while the sum is 35.

The square root of 81087173 is about 9004.8416421390. The cubic root of 81087173 is about 432.8300317669.

The spelling of 81087173 in words is "eighty-one million, eighty-seven thousand, one hundred seventy-three".