216645251 has 2 divisors, whose sum is σ = 216645252. Its totient is φ = 216645250.

The previous prime is 216645203. The next prime is 216645269. The reversal of 216645251 is 152546612.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 216645251 - 2¹⁰ = 216644227 is a prime.

It is not a weakly prime, because it can be changed into another prime (216645151) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 108322625 + 108322626.

It is an arithmetic number, because the mean of its divisors is an integer number (108322626).

Almost surely, 2^216645251 is an apocalyptic number.

216645251 is a deficient number, since it is larger than the sum of its proper divisors (1).

216645251 is an equidigital number, since it uses as much as digits as its factorization.

216645251 is an evil number, because the sum of its binary digits is even.

The product of its digits is 14400, while the sum is 32.

The square root of 216645251 is about 14718.8739718771. The cubic root of 216645251 is about 600.5968606949.

The spelling of 216645251 in words is "two hundred sixteen million, six hundred forty-five thousand, two hundred fifty-one".