20229991 has 2 divisors, whose sum is σ = 20229992. Its totient is φ = 20229990.

The previous prime is 20229977. The next prime is 20230031. The reversal of 20229991 is 19992202.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 20229991 - 2⁷ = 20229863 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (20229901) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10114995 + 10114996.

It is an arithmetic number, because the mean of its divisors is an integer number (10114996).

Almost surely, 2^20229991 is an apocalyptic number.

20229991 is a deficient number, since it is larger than the sum of its proper divisors (1).

20229991 is an equidigital number, since it uses as much as digits as its factorization.

20229991 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 5832, while the sum is 34.

The square root of 20229991 is about 4497.7762283155. The cubic root of 20229991 is about 272.4782846091.

The spelling of 20229991 in words is "twenty million, two hundred twenty-nine thousand, nine hundred ninety-one".