221515237 has 2 divisors, whose sum is σ = 221515238. Its totient is φ = 221515236.

The previous prime is 221515193. The next prime is 221515241. The reversal of 221515237 is 732515122.

221515237 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 149842081 + 71673156 = 12241^2 + 8466^2 .

It is a cyclic number.

It is not a de Polignac number, because 221515237 - 2⁷ = 221515109 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (221515537) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 110757618 + 110757619.

It is an arithmetic number, because the mean of its divisors is an integer number (110757619).

Almost surely, 2^221515237 is an apocalyptic number.

It is an amenable number.

221515237 is a deficient number, since it is larger than the sum of its proper divisors (1).

221515237 is an equidigital number, since it uses as much as digits as its factorization.

221515237 is an evil number, because the sum of its binary digits is even.

The product of its digits is 4200, while the sum is 28.

The square root of 221515237 is about 14883.3879543604. The cubic root of 221515237 is about 605.0638431818.

The spelling of 221515237 in words is "two hundred twenty-one million, five hundred fifteen thousand, two hundred thirty-seven".