72172651536721 has 2 divisors, whose sum is σ = 72172651536722. Its totient is φ = 72172651536720.

The previous prime is 72172651536599. The next prime is 72172651536757. The reversal of 72172651536721 is 12763515627127.

It is a happy number.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 66336871115025 + 5835780421696 = 8144745^2 + 2415736^2 .

It is a cyclic number.

It is not a de Polignac number, because 72172651536721 - 2⁴³ = 63376558514513 is a prime.

It is a super-2 number, since 2×72172651536721² (a number of 29 digits) contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (72172651536121) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 36086325768360 + 36086325768361.

It is an arithmetic number, because the mean of its divisors is an integer number (36086325768361).

Almost surely, 2^{72172651536721} is an apocalyptic number.

It is an amenable number.

72172651536721 is a deficient number, since it is larger than the sum of its proper divisors (1).

72172651536721 is an equidigital number, since it uses as much as digits as its factorization.

72172651536721 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 7408800, while the sum is 55.

The spelling of 72172651536721 in words is "seventy-two trillion, one hundred seventy-two billion, six hundred fifty-one million, five hundred thirty-six thousand, seven hundred twenty-one".