20917187 has 2 divisors, whose sum is σ = 20917188. Its totient is φ = 20917186.

The previous prime is 20917181. The next prime is 20917223. The reversal of 20917187 is 78171902.

It is a weak prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-20917187 is a prime.

It is not a weakly prime, because it can be changed into another prime (20917181) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10458593 + 10458594.

It is an arithmetic number, because the mean of its divisors is an integer number (10458594).

Almost surely, 2^20917187 is an apocalyptic number.

20917187 is a deficient number, since it is larger than the sum of its proper divisors (1).

20917187 is an equidigital number, since it uses as much as digits as its factorization.

20917187 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 7056, while the sum is 35.

The square root of 20917187 is about 4573.5311303193. The cubic root of 20917187 is about 275.5292814860.

The spelling of 20917187 in words is "twenty million, nine hundred seventeen thousand, one hundred eighty-seven".