72945221 has 2 divisors, whose sum is σ = 72945222. Its totient is φ = 72945220.

The previous prime is 72945211. The next prime is 72945227. The reversal of 72945221 is 12254927.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 70728100 + 2217121 = 8410^2 + 1489^2 .

It is an emirp because it is prime and its reverse (12254927) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 72945221 - 2¹⁰ = 72944197 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (72945227) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 36472610 + 36472611.

It is an arithmetic number, because the mean of its divisors is an integer number (36472611).

Almost surely, 2^72945221 is an apocalyptic number.

It is an amenable number.

72945221 is a deficient number, since it is larger than the sum of its proper divisors (1).

72945221 is an equidigital number, since it uses as much as digits as its factorization.

72945221 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 10080, while the sum is 32.

The square root of 72945221 is about 8540.7974452038. The cubic root of 72945221 is about 417.8293546559.

The spelling of 72945221 in words is "seventy-two million, nine hundred forty-five thousand, two hundred twenty-one".