20731091 has 2 divisors, whose sum is σ = 20731092. Its totient is φ = 20731090.

The previous prime is 20731069. The next prime is 20731097. The reversal of 20731091 is 19013702.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 20731091 - 2¹⁰ = 20730067 is a prime.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (20731097) 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, 10365545 + 10365546.

It is an arithmetic number, because the mean of its divisors is an integer number (10365546).

Almost surely, 2^20731091 is an apocalyptic number.

20731091 is a deficient number, since it is larger than the sum of its proper divisors (1).

20731091 is an equidigital number, since it uses as much as digits as its factorization.

20731091 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 378, while the sum is 23.

The square root of 20731091 is about 4553.1407841181. The cubic root of 20731091 is about 274.7097367093.

Adding to 20731091 its reverse (19013702), we get a palindrome (39744793).

The spelling of 20731091 in words is "twenty million, seven hundred thirty-one thousand, ninety-one".