217812949 has 2 divisors, whose sum is σ = 217812950. Its totient is φ = 217812948.

The previous prime is 217812943. The next prime is 217812961. The reversal of 217812949 is 949218712.

It is a happy number.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 159213924 + 58599025 = 12618^2 + 7655^2 .

It is a cyclic number.

It is not a de Polignac number, because 217812949 - 2¹³ = 217804757 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (217812943) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 108906474 + 108906475.

It is an arithmetic number, because the mean of its divisors is an integer number (108906475).

Almost surely, 2^217812949 is an apocalyptic number.

It is an amenable number.

217812949 is a deficient number, since it is larger than the sum of its proper divisors (1).

217812949 is an equidigital number, since it uses as much as digits as its factorization.

217812949 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 72576, while the sum is 43.

The square root of 217812949 is about 14758.4873547393. The cubic root of 217812949 is about 601.6739817798.

The spelling of 217812949 in words is "two hundred seventeen million, eight hundred twelve thousand, nine hundred forty-nine".