20316991 has 2 divisors, whose sum is σ = 20316992. Its totient is φ = 20316990.

The previous prime is 20316977. The next prime is 20317021. The reversal of 20316991 is 19961302.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 20316991 - 2¹⁵ = 20284223 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (20316911) 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, 10158495 + 10158496.

It is an arithmetic number, because the mean of its divisors is an integer number (10158496).

Almost surely, 2^20316991 is an apocalyptic number.

20316991 is a deficient number, since it is larger than the sum of its proper divisors (1).

20316991 is an equidigital number, since it uses as much as digits as its factorization.

20316991 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 2916, while the sum is 31.

The square root of 20316991 is about 4507.4372985101. The cubic root of 20316991 is about 272.8683277776.

The spelling of 20316991 in words is "twenty million, three hundred sixteen thousand, nine hundred ninety-one".