217611668 has 6 divisors (see below), whose sum is σ = 380820426. Its totient is φ = 108805832.

The previous prime is 217611649. The next prime is 217611701. The reversal of 217611668 is 866116712.

It can be written as a sum of positive squares in only one way, i.e., 176677264 + 40934404 = 13292^2 + 6398^2 .

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 27201455 + ... + 27201462.

It is an arithmetic number, because the mean of its divisors is an integer number (63470071).

Almost surely, 2^217611668 is an apocalyptic number.

It is an amenable number.

217611668 is a deficient number, since it is larger than the sum of its proper divisors (163208758).

217611668 is a wasteful number, since it uses less digits than its factorization.

217611668 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 54402921 (or 54402919 counting only the distinct ones).

The product of its digits is 24192, while the sum is 38.

The square root of 217611668 is about 14751.6666177080. Note that the first 4 decimals coincide. The cubic root of 217611668 is about 601.4885889691.

The spelling of 217611668 in words is "two hundred seventeen million, six hundred eleven thousand, six hundred sixty-eight".