191140021 has 2 divisors, whose sum is σ = 191140022. Its totient is φ = 191140020.

The previous prime is 191140013. The next prime is 191140069. The reversal of 191140021 is 120041191.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 155975121 + 35164900 = 12489^2 + 5930^2 .

It is a cyclic number.

It is not a de Polignac number, because 191140021 - 2³ = 191140013 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (191140091) 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, 95570010 + 95570011.

It is an arithmetic number, because the mean of its divisors is an integer number (95570011).

Almost surely, 2^191140021 is an apocalyptic number.

It is an amenable number.

191140021 is a deficient number, since it is larger than the sum of its proper divisors (1).

191140021 is an equidigital number, since it uses as much as digits as its factorization.

191140021 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 72, while the sum is 19.

The square root of 191140021 is about 13825.3398149919. The cubic root of 191140021 is about 576.0372164820.

The spelling of 191140021 in words is "one hundred ninety-one million, one hundred forty thousand, twenty-one".