20431091 has 2 divisors, whose sum is σ = 20431092. Its totient is φ = 20431090.

The previous prime is 20431087. The next prime is 20431097. The reversal of 20431091 is 19013402.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 20431091 - 2² = 20431087 is a prime.

It is a Sophie Germain prime.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (20431097) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10215545 + 10215546.

It is an arithmetic number, because the mean of its divisors is an integer number (10215546).

Almost surely, 2^20431091 is an apocalyptic number.

20431091 is a deficient number, since it is larger than the sum of its proper divisors (1).

20431091 is an equidigital number, since it uses as much as digits as its factorization.

20431091 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 216, while the sum is 20.

The square root of 20431091 is about 4520.0764374068. The cubic root of 20431091 is about 273.3781830364.

Adding to 20431091 its reverse (19013402), we get a palindrome (39444493).

The spelling of 20431091 in words is "twenty million, four hundred thirty-one thousand, ninety-one".