20917191 has 8 divisors (see below), whose sum is σ = 29530224. Its totient is φ = 13124480.

The previous prime is 20917187. The next prime is 20917223. The reversal of 20917191 is 19171902.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 20917191 - 2² = 20917187 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20917121) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 205020 + ... + 205121.

It is an arithmetic number, because the mean of its divisors is an integer number (3691278).

Almost surely, 2^20917191 is an apocalyptic number.

20917191 is a deficient number, since it is larger than the sum of its proper divisors (8613033).

20917191 is a wasteful number, since it uses less digits than its factorization.

20917191 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 410161.

The product of its (nonzero) digits is 1134, while the sum is 30.

The square root of 20917191 is about 4573.5315676182. The cubic root of 20917191 is about 275.5292990492.

The spelling of 20917191 in words is "twenty million, nine hundred seventeen thousand, one hundred ninety-one".