72161891 has 2 divisors, whose sum is σ = 72161892. Its totient is φ = 72161890.

The previous prime is 72161849. The next prime is 72161911. The reversal of 72161891 is 19816127.

It is a strong prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-72161891 is a prime.

It is not a weakly prime, because it can be changed into another prime (72161801) by changing a digit.

It is a good prime.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 36080945 + 36080946.

It is an arithmetic number, because the mean of its divisors is an integer number (36080946).

Almost surely, 2^72161891 is an apocalyptic number.

72161891 is a deficient number, since it is larger than the sum of its proper divisors (1).

72161891 is an equidigital number, since it uses as much as digits as its factorization.

72161891 is an evil number, because the sum of its binary digits is even.

The product of its digits is 6048, while the sum is 35.

The square root of 72161891 is about 8494.8155365493. The cubic root of 72161891 is about 416.3283338463.

The spelling of 72161891 in words is "seventy-two million, one hundred sixty-one thousand, eight hundred ninety-one".