19997597 has 2 divisors, whose sum is σ = 19997598. Its totient is φ = 19997596.

The previous prime is 19997591. The next prime is 19997599. The reversal of 19997597 is 79579991.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 19945156 + 52441 = 4466^2 + 229^2 .

It is a cyclic number.

It is not a de Polignac number, because 19997597 - 2⁴ = 19997581 is a prime.

Together with 19997599, it forms a pair of twin primes.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (19997591) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 9998798 + 9998799.

It is an arithmetic number, because the mean of its divisors is an integer number (9998799).

Almost surely, 2^19997597 is an apocalyptic number.

It is an amenable number.

19997597 is a deficient number, since it is larger than the sum of its proper divisors (1).

19997597 is an equidigital number, since it uses as much as digits as its factorization.

19997597 is an evil number, because the sum of its binary digits is even.

The product of its digits is 1607445, while the sum is 56.

The square root of 19997597 is about 4471.8672833616. The cubic root of 19997597 is about 271.4308899815.

The spelling of 19997597 in words is "nineteen million, nine hundred ninety-seven thousand, five hundred ninety-seven".