19997071 has 2 divisors, whose sum is σ = 19997072. Its totient is φ = 19997070.

The previous prime is 19997069. The next prime is 19997093. The reversal of 19997071 is 17079991.

It is a weak prime.

It is an emirp because it is prime and its reverse (17079991) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 19997071 - 2¹ = 19997069 is a prime.

Together with 19997069, it forms a pair of twin primes.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (19997011) 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, 9998535 + 9998536.

It is an arithmetic number, because the mean of its divisors is an integer number (9998536).

Almost surely, 2^19997071 is an apocalyptic number.

19997071 is a deficient number, since it is larger than the sum of its proper divisors (1).

19997071 is an equidigital number, since it uses as much as digits as its factorization.

19997071 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 35721, while the sum is 43.

The square root of 19997071 is about 4471.8084708538. The cubic root of 19997071 is about 271.4285101306.

The spelling of 19997071 in words is "nineteen million, nine hundred ninety-seven thousand, seventy-one".