72729521 has 2 divisors, whose sum is σ = 72729522. Its totient is φ = 72729520.

The previous prime is 72729499. The next prime is 72729529. The reversal of 72729521 is 12592727.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 71656225 + 1073296 = 8465^2 + 1036^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-72729521 is a prime.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (72729529) 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, 36364760 + 36364761.

It is an arithmetic number, because the mean of its divisors is an integer number (36364761).

Almost surely, 2^72729521 is an apocalyptic number.

It is an amenable number.

72729521 is a deficient number, since it is larger than the sum of its proper divisors (1).

72729521 is an equidigital number, since it uses as much as digits as its factorization.

72729521 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 17640, while the sum is 35.

The square root of 72729521 is about 8528.1604698786. The cubic root of 72729521 is about 417.4171057054.

The spelling of 72729521 in words is "seventy-two million, seven hundred twenty-nine thousand, five hundred twenty-one".