221501237 has 2 divisors, whose sum is σ = 221501238. Its totient is φ = 221501236.

The previous prime is 221501207. The next prime is 221501239. The reversal of 221501237 is 732105122.

It is a happy number.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 175138756 + 46362481 = 13234^2 + 6809^2 .

It is a cyclic number.

It is not a de Polignac number, because 221501237 - 2¹⁶ = 221435701 is a prime.

Together with 221501239, it forms a pair of twin primes.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (221501239) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 110750618 + 110750619.

It is an arithmetic number, because the mean of its divisors is an integer number (110750619).

Almost surely, 2^221501237 is an apocalyptic number.

It is an amenable number.

221501237 is a deficient number, since it is larger than the sum of its proper divisors (1).

221501237 is an equidigital number, since it uses as much as digits as its factorization.

221501237 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 840, while the sum is 23.

The square root of 221501237 is about 14882.9176239069. The cubic root of 221501237 is about 605.0510960192.

Adding to 221501237 its reverse (732105122), we get a palindrome (953606359).

The spelling of 221501237 in words is "two hundred twenty-one million, five hundred one thousand, two hundred thirty-seven".