216997257 has 4 divisors (see below), whose sum is σ = 289329680. Its totient is φ = 144664836.

The previous prime is 216997243. The next prime is 216997283. The reversal of 216997257 is 752799612.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is not a de Polignac number, because 216997257 - 2¹⁰ = 216996233 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (216997217) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 36166207 + ... + 36166212.

It is an arithmetic number, because the mean of its divisors is an integer number (72332420).

Almost surely, 2^216997257 is an apocalyptic number.

It is an amenable number.

216997257 is a deficient number, since it is larger than the sum of its proper divisors (72332423).

216997257 is an equidigital number, since it uses as much as digits as its factorization.

216997257 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 72332422.

The product of its digits is 476280, while the sum is 48.

The square root of 216997257 is about 14730.8267588754. The cubic root of 216997257 is about 600.9219686751.

The spelling of 216997257 in words is "two hundred sixteen million, nine hundred ninety-seven thousand, two hundred fifty-seven".