72165991 has 2 divisors, whose sum is σ = 72165992. Its totient is φ = 72165990.

The previous prime is 72165953. The next prime is 72166051. The reversal of 72165991 is 19956127.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 72165991 - 2²¹ = 70068839 is a prime.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (72165931) 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 as a sum of consecutive naturals, namely, 36082995 + 36082996.

It is an arithmetic number, because the mean of its divisors is an integer number (36082996).

Almost surely, 2^72165991 is an apocalyptic number.

72165991 is a deficient number, since it is larger than the sum of its proper divisors (1).

72165991 is an equidigital number, since it uses as much as digits as its factorization.

72165991 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 34020, while the sum is 40.

The square root of 72165991 is about 8495.0568567844. The cubic root of 72165991 is about 416.3362184967.

The spelling of 72165991 in words is "seventy-two million, one hundred sixty-five thousand, nine hundred ninety-one".