72321731 has 2 divisors, whose sum is σ = 72321732. Its totient is φ = 72321730.

The previous prime is 72321719. The next prime is 72321749. The reversal of 72321731 is 13712327.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 72321731 - 2¹⁴ = 72305347 is a prime.

It is a super-2 number, since 2×72321731² = 10460865549672722, which contains 22 as substring.

It is a self number, because there is not a number n which added to its sum of digits gives 72321731.

It is not a weakly prime, because it can be changed into another prime (72321701) 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, 36160865 + 36160866.

It is an arithmetic number, because the mean of its divisors is an integer number (36160866).

Almost surely, 2^72321731 is an apocalyptic number.

72321731 is a deficient number, since it is larger than the sum of its proper divisors (1).

72321731 is an equidigital number, since it uses as much as digits as its factorization.

72321731 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 1764, while the sum is 26.

The square root of 72321731 is about 8504.2184238177. The cubic root of 72321731 is about 416.6354989664.

The spelling of 72321731 in words is "seventy-two million, three hundred twenty-one thousand, seven hundred thirty-one".