20817091 has 2 divisors, whose sum is σ = 20817092. Its totient is φ = 20817090.

The previous prime is 20817077. The next prime is 20817107. The reversal of 20817091 is 19071802.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 20817091 - 2⁵ = 20817059 is a prime.

It is a super-3 number, since 3×20817091³ (a number of 23 digits) contains 333 as substring.

It is not a weakly prime, because it can be changed into another prime (20817491) 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, 10408545 + 10408546.

It is an arithmetic number, because the mean of its divisors is an integer number (10408546).

Almost surely, 2^20817091 is an apocalyptic number.

20817091 is a deficient number, since it is larger than the sum of its proper divisors (1).

20817091 is an equidigital number, since it uses as much as digits as its factorization.

20817091 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 1008, while the sum is 28.

The square root of 20817091 is about 4562.5750404788. The cubic root of 20817091 is about 275.0890774792.

Adding to 20817091 its reverse (19071802), we get a palindrome (39888893).

The spelling of 20817091 in words is "twenty million, eight hundred seventeen thousand, ninety-one".