20731187 has 2 divisors, whose sum is σ = 20731188. Its totient is φ = 20731186.

The previous prime is 20731163. The next prime is 20731189. The reversal of 20731187 is 78113702.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 20731187 - 2¹⁴ = 20714803 is a prime.

It is a super-2 number, since 2×20731187² = 859564228857938, which contains 22 as substring.

Together with 20731189, it forms a pair of twin primes.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (20731189) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10365593 + 10365594.

It is an arithmetic number, because the mean of its divisors is an integer number (10365594).

Almost surely, 2^20731187 is an apocalyptic number.

20731187 is a deficient number, since it is larger than the sum of its proper divisors (1).

20731187 is an equidigital number, since it uses as much as digits as its factorization.

20731187 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 2352, while the sum is 29.

The square root of 20731187 is about 4553.1513262794. The cubic root of 20731187 is about 274.7101607438.

Adding to 20731187 its reverse (78113702), we get a palindrome (98844889).

The spelling of 20731187 in words is "twenty million, seven hundred thirty-one thousand, one hundred eighty-seven".