217940391850 has 24 divisors (see below), whose sum is σ = 429214373388. Its totient is φ = 82048147200.

The previous prime is 217940391839. The next prime is 217940391863. The reversal of 217940391850 is 58193049712.

It is a happy number.

It can be written as a sum of positive squares in 6 ways, for example, as 164504059281 + 53436332569 = 405591^2 + 231163^2 .

It is a junction number, because it is equal to n+sod(n) for n = 217940391794 and 217940391803.

It is an unprimeable number.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 128199381 + ... + 128201080.

Almost surely, 2^217940391850 is an apocalyptic number.

217940391850 is a deficient number, since it is larger than the sum of its proper divisors (211273981538).

217940391850 is a wasteful number, since it uses less digits than its factorization.

217940391850 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 256400490 (or 256400485 counting only the distinct ones).

The product of its (nonzero) digits is 544320, while the sum is 49.

The spelling of 217940391850 in words is "two hundred seventeen billion, nine hundred forty million, three hundred ninety-one thousand, eight hundred fifty".