216691917 has 16 divisors (see below), whose sum is σ = 311418240. Its totient is φ = 133232832.

The previous prime is 216691913. The next prime is 216691927. The reversal of 216691917 is 719196612.

It is not a de Polignac number, because 216691917 - 2² = 216691913 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (216691913) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 71803 + ... + 74759.

It is an arithmetic number, because the mean of its divisors is an integer number (19463640).

Almost surely, 2^216691917 is an apocalyptic number.

It is an amenable number.

216691917 is a deficient number, since it is larger than the sum of its proper divisors (94726323).

216691917 is a wasteful number, since it uses less digits than its factorization.

216691917 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4852.

The product of its digits is 40824, while the sum is 42.

The square root of 216691917 is about 14720.4591300679. The cubic root of 216691917 is about 600.6399810200.

The spelling of 216691917 in words is "two hundred sixteen million, six hundred ninety-one thousand, nine hundred seventeen".