19197991 has 2 divisors, whose sum is σ = 19197992. Its totient is φ = 19197990.

The previous prime is 19197973. The next prime is 19198057. The reversal of 19197991 is 19979191.

It is a happy number.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 19197991 - 2¹³ = 19189799 is a prime.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (19197691) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 9598995 + 9598996.

It is an arithmetic number, because the mean of its divisors is an integer number (9598996).

Almost surely, 2^19197991 is an apocalyptic number.

19197991 is a deficient number, since it is larger than the sum of its proper divisors (1).

19197991 is an equidigital number, since it uses as much as digits as its factorization.

19197991 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 45927, while the sum is 46.

The square root of 19197991 is about 4381.5512093321. The cubic root of 19197991 is about 267.7638401877.

The spelling of 19197991 in words is "nineteen million, one hundred ninety-seven thousand, nine hundred ninety-one".