217994957 has 2 divisors, whose sum is σ = 217994958. Its totient is φ = 217994956.

The previous prime is 217994899. The next prime is 217994969. The reversal of 217994957 is 759499712.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 180123241 + 37871716 = 13421^2 + 6154^2 .

It is a cyclic number.

It is not a de Polignac number, because 217994957 - 2⁸ = 217994701 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 217994899 and 217994908.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (217994857) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 108997478 + 108997479.

It is an arithmetic number, because the mean of its divisors is an integer number (108997479).

Almost surely, 2^217994957 is an apocalyptic number.

It is an amenable number.

217994957 is a deficient number, since it is larger than the sum of its proper divisors (1).

217994957 is an equidigital number, since it uses as much as digits as its factorization.

217994957 is an evil number, because the sum of its binary digits is even.

The product of its digits is 1428840, while the sum is 53.

The square root of 217994957 is about 14764.6522817166. The cubic root of 217994957 is about 601.8415246036.

The spelling of 217994957 in words is "two hundred seventeen million, nine hundred ninety-four thousand, nine hundred fifty-seven".