72199991 has 2 divisors, whose sum is σ = 72199992. Its totient is φ = 72199990.

The previous prime is 72199973. The next prime is 72199997. The reversal of 72199991 is 19999127.

It is a happy number.

It is a strong prime.

It is an emirp because it is prime and its reverse (19999127) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 72199991 - 2¹⁰ = 72198967 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (72199997) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 36099995 + 36099996.

It is an arithmetic number, because the mean of its divisors is an integer number (36099996).

Almost surely, 2^72199991 is an apocalyptic number.

72199991 is a deficient number, since it is larger than the sum of its proper divisors (1).

72199991 is an equidigital number, since it uses as much as digits as its factorization.

72199991 is an evil number, because the sum of its binary digits is even.

The product of its digits is 91854, while the sum is 47.

The square root of 72199991 is about 8497.0577849041. The cubic root of 72199991 is about 416.4015918984.

The spelling of 72199991 in words is "seventy-two million, one hundred ninety-nine thousand, nine hundred ninety-one".