81972179 has 4 divisors (see below), whose sum is σ = 81990384. Its totient is φ = 81953976.

The previous prime is 81972167. The next prime is 81972203. The reversal of 81972179 is 97127918.

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

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-81972179 is a prime.

It is a super-3 number, since 3×81972179³ (a number of 25 digits) contains 333 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (81972109) 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, 3149 + ... + 13185.

It is an arithmetic number, because the mean of its divisors is an integer number (20497596).

Almost surely, 2^81972179 is an apocalyptic number.

81972179 is a deficient number, since it is larger than the sum of its proper divisors (18205).

81972179 is a wasteful number, since it uses less digits than its factorization.

81972179 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 18204.

The product of its digits is 63504, while the sum is 44.

The square root of 81972179 is about 9053.8488500748. The cubic root of 81972179 is about 434.3990097592.

The spelling of 81972179 in words is "eighty-one million, nine hundred seventy-two thousand, one hundred seventy-nine".