72121647691 has 2 divisors, whose sum is σ = 72121647692. Its totient is φ = 72121647690.

The previous prime is 72121647641. The next prime is 72121647757. The reversal of 72121647691 is 19674612127.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 72121647691 - 2¹⁵ = 72121614923 is a prime.

It is not a weakly prime, because it can be changed into another prime (72121647641) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 36060823845 + 36060823846.

It is an arithmetic number, because the mean of its divisors is an integer number (36060823846).

Almost surely, 2^72121647691 is an apocalyptic number.

72121647691 is a deficient number, since it is larger than the sum of its proper divisors (1).

72121647691 is an equidigital number, since it uses as much as digits as its factorization.

72121647691 is an evil number, because the sum of its binary digits is even.

The product of its digits is 254016, while the sum is 46.

The spelling of 72121647691 in words is "seventy-two billion, one hundred twenty-one million, six hundred forty-seven thousand, six hundred ninety-one".