215221247 has 2 divisors, whose sum is σ = 215221248. Its totient is φ = 215221246.

The previous prime is 215221231. The next prime is 215221249. The reversal of 215221247 is 742122512.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 215221247 - 2⁴ = 215221231 is a prime.

Together with 215221249, 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 (215221249) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 107610623 + 107610624.

It is an arithmetic number, because the mean of its divisors is an integer number (107610624).

Almost surely, 2^215221247 is an apocalyptic number.

215221247 is a deficient number, since it is larger than the sum of its proper divisors (1).

215221247 is an equidigital number, since it uses as much as digits as its factorization.

215221247 is an evil number, because the sum of its binary digits is even.

The product of its digits is 2240, while the sum is 26.

The square root of 215221247 is about 14670.4208187768. The cubic root of 215221247 is about 599.2780641034.

Adding to 215221247 its reverse (742122512), we get a palindrome (957343759).

The spelling of 215221247 in words is "two hundred fifteen million, two hundred twenty-one thousand, two hundred forty-seven".