73721209 has 2 divisors, whose sum is σ = 73721210. Its totient is φ = 73721208.

The previous prime is 73721173. The next prime is 73721243. The reversal of 73721209 is 90212737.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 52881984 + 20839225 = 7272^2 + 4565^2 .

It is an emirp because it is prime and its reverse (90212737) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 73721209 - 2¹⁷ = 73590137 is a prime.

It is not a weakly prime, because it can be changed into another prime (73721269) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 36860604 + 36860605.

It is an arithmetic number, because the mean of its divisors is an integer number (36860605).

Almost surely, 2^73721209 is an apocalyptic number.

It is an amenable number.

73721209 is a deficient number, since it is larger than the sum of its proper divisors (1).

73721209 is an equidigital number, since it uses as much as digits as its factorization.

73721209 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 5292, while the sum is 31.

The square root of 73721209 is about 8586.1055782002. The cubic root of 73721209 is about 419.3057483619.

The spelling of 73721209 in words is "seventy-three million, seven hundred twenty-one thousand, two hundred nine".