71998181 has 4 divisors (see below), whose sum is σ = 72363852. Its totient is φ = 71632512.

The previous prime is 71998177. The next prime is 71998187. The reversal of 71998181 is 18189917.

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 59985025 + 12013156 = 7745^2 + 3466^2 .

It is a cyclic number.

It is not a de Polignac number, because 71998181 - 2² = 71998177 is a prime.

It is a super-2 number, since 2×71998181² = 10367476134617522, which contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (71998187) 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, 182540 + ... + 182933.

It is an arithmetic number, because the mean of its divisors is an integer number (18090963).

Almost surely, 2^71998181 is an apocalyptic number.

It is an amenable number.

71998181 is a deficient number, since it is larger than the sum of its proper divisors (365671).

71998181 is a wasteful number, since it uses less digits than its factorization.

71998181 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 365670.

The product of its digits is 36288, while the sum is 44.

The square root of 71998181 is about 8485.1741879587. The cubic root of 71998181 is about 416.0132611804.

The spelling of 71998181 in words is "seventy-one million, nine hundred ninety-eight thousand, one hundred eighty-one".