20198257091 has 2 divisors, whose sum is σ = 20198257092. Its totient is φ = 20198257090.

The previous prime is 20198257061. The next prime is 20198257129. The reversal of 20198257091 is 19075289102.

It is a happy number.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 20198257091 - 2²² = 20194062787 is a prime.

It is a Sophie Germain prime.

It is not a weakly prime, because it can be changed into another prime (20198257061) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10099128545 + 10099128546.

It is an arithmetic number, because the mean of its divisors is an integer number (10099128546).

Almost surely, 2^20198257091 is an apocalyptic number.

20198257091 is a deficient number, since it is larger than the sum of its proper divisors (1).

20198257091 is an equidigital number, since it uses as much as digits as its factorization.

20198257091 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 90720, while the sum is 44.

The spelling of 20198257091 in words is "twenty billion, one hundred ninety-eight million, two hundred fifty-seven thousand, ninety-one".