72121691 has 2 divisors, whose sum is σ = 72121692. Its totient is φ = 72121690.

The previous prime is 72121639. The next prime is 72121697. The reversal of 72121691 is 19612127.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 72121691 - 2¹⁰ = 72120667 is a prime.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (72121697) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 36060845 + 36060846.

It is an arithmetic number, because the mean of its divisors is an integer number (36060846).

Almost surely, 2^72121691 is an apocalyptic number.

72121691 is a deficient number, since it is larger than the sum of its proper divisors (1).

72121691 is an equidigital number, since it uses as much as digits as its factorization.

72121691 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 1512, while the sum is 29.

The square root of 72121691 is about 8492.4490578396. The cubic root of 72121691 is about 416.2510099865.

The spelling of 72121691 in words is "seventy-two million, one hundred twenty-one thousand, six hundred ninety-one".