19997897 has 2 divisors, whose sum is σ = 19997898. Its totient is φ = 19997896.

The previous prime is 19997893. The next prime is 19997911. The reversal of 19997897 is 79879991.

It is a happy number.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 18567481 + 1430416 = 4309^2 + 1196^2 .

It is a cyclic number.

It is not a de Polignac number, because 19997897 - 2² = 19997893 is a prime.

It is not a weakly prime, because it can be changed into another prime (19997893) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 9998948 + 9998949.

It is an arithmetic number, because the mean of its divisors is an integer number (9998949).

Almost surely, 2^19997897 is an apocalyptic number.

It is an amenable number.

19997897 is a deficient number, since it is larger than the sum of its proper divisors (1).

19997897 is an equidigital number, since it uses as much as digits as its factorization.

19997897 is an evil number, because the sum of its binary digits is even.

The product of its digits is 2571912, while the sum is 59.

The square root of 19997897 is about 4471.9008262706. The cubic root of 19997897 is about 271.4322472923.

The spelling of 19997897 in words is "nineteen million, nine hundred ninety-seven thousand, eight hundred ninety-seven".