72171881 has 2 divisors, whose sum is σ = 72171882. Its totient is φ = 72171880.

The previous prime is 72171871. The next prime is 72171901. The reversal of 72171881 is 18817127.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 61387225 + 10784656 = 7835^2 + 3284^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-72171881 is a prime.

It is a super-2 number, since 2×72171881² = 10417560814156322, which contains 22 as substring.

It is a Sophie Germain prime.

It is a Curzon number.

It is not a weakly prime, because it can be changed into another prime (72171871) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 36085940 + 36085941.

It is an arithmetic number, because the mean of its divisors is an integer number (36085941).

Almost surely, 2^72171881 is an apocalyptic number.

It is an amenable number.

72171881 is a deficient number, since it is larger than the sum of its proper divisors (1).

72171881 is an equidigital number, since it uses as much as digits as its factorization.

72171881 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 6272, while the sum is 35.

The square root of 72171881 is about 8495.4035219052. The cubic root of 72171881 is about 416.3475449474.

The spelling of 72171881 in words is "seventy-two million, one hundred seventy-one thousand, eight hundred eighty-one".