81667165 has 4 divisors (see below), whose sum is σ = 98000604. Its totient is φ = 65333728.

The previous prime is 81667141. The next prime is 81667169. The reversal of 81667165 is 56176618.

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 19035769 + 62631396 = 4363^2 + 7914^2 .

It is a cyclic number.

It is not a de Polignac number, because 81667165 - 2⁹ = 81666653 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 (81667169) 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, 8166712 + ... + 8166721.

It is an arithmetic number, because the mean of its divisors is an integer number (24500151).

Almost surely, 2^81667165 is an apocalyptic number.

It is an amenable number.

81667165 is a deficient number, since it is larger than the sum of its proper divisors (16333439).

81667165 is a wasteful number, since it uses less digits than its factorization.

81667165 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 16333438.

The product of its digits is 60480, while the sum is 40.

The square root of 81667165 is about 9036.9887130614. The cubic root of 81667165 is about 433.8595484414.

The spelling of 81667165 in words is "eighty-one million, six hundred sixty-seven thousand, one hundred sixty-five".