216821273 has 2 divisors, whose sum is σ = 216821274. Its totient is φ = 216821272.

The previous prime is 216821257. The next prime is 216821303. The reversal of 216821273 is 372128612.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 215884249 + 937024 = 14693^2 + 968^2 .

It is a cyclic number.

It is not a de Polignac number, because 216821273 - 2⁴ = 216821257 is a prime.

It is a super-2 number, since 2×216821273² = 94022928850681058, which contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (216821233) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 108410636 + 108410637.

It is an arithmetic number, because the mean of its divisors is an integer number (108410637).

Almost surely, 2^216821273 is an apocalyptic number.

It is an amenable number.

216821273 is a deficient number, since it is larger than the sum of its proper divisors (1).

216821273 is an equidigital number, since it uses as much as digits as its factorization.

216821273 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 8064, while the sum is 32.

The square root of 216821273 is about 14724.8522233671. The cubic root of 216821273 is about 600.7594762171.

Adding to 216821273 its reverse (372128612), we get a palindrome (588949885).

The spelling of 216821273 in words is "two hundred sixteen million, eight hundred twenty-one thousand, two hundred seventy-three".