81371005 has 4 divisors (see below), whose sum is σ = 97645212. Its totient is φ = 65096800.

The previous prime is 81370997. The next prime is 81371021. The reversal of 81371005 is 50017318.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 40487769 + 40883236 = 6363^2 + 6394^2 .

It is not a de Polignac number, because 81371005 - 2³ = 81370997 is a prime.

It is a Duffinian number.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 8137096 + ... + 8137105.

It is an arithmetic number, because the mean of its divisors is an integer number (24411303).

Almost surely, 2^81371005 is an apocalyptic number.

It is an amenable number.

81371005 is a deficient number, since it is larger than the sum of its proper divisors (16274207).

81371005 is a wasteful number, since it uses less digits than its factorization.

81371005 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 16274206.

The product of its (nonzero) digits is 840, while the sum is 25.

The square root of 81371005 is about 9020.5878411554. The cubic root of 81371005 is about 433.3344598919.

The spelling of 81371005 in words is "eighty-one million, three hundred seventy-one thousand, five".