72015221 has 2 divisors, whose sum is σ = 72015222. Its totient is φ = 72015220.

The previous prime is 72015211. The next prime is 72015253. The reversal of 72015221 is 12251027.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 72012196 + 3025 = 8486^2 + 55^2 .

It is a cyclic number.

It is not a de Polignac number, because 72015221 - 2¹⁴ = 71998837 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 72015193 and 72015202.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (72015211) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 36007610 + 36007611.

It is an arithmetic number, because the mean of its divisors is an integer number (36007611).

Almost surely, 2^72015221 is an apocalyptic number.

It is an amenable number.

72015221 is a deficient number, since it is larger than the sum of its proper divisors (1).

72015221 is an equidigital number, since it uses as much as digits as its factorization.

72015221 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 280, while the sum is 20.

The square root of 72015221 is about 8486.1782328678. The cubic root of 72015221 is about 416.0460782447.

Adding to 72015221 its reverse (12251027), we get a palindrome (84266248).

The spelling of 72015221 in words is "seventy-two million, fifteen thousand, two hundred twenty-one".