19990897 has 2 divisors, whose sum is σ = 19990898. Its totient is φ = 19990896.

The previous prime is 19990891. The next prime is 19990931. The reversal of 19990897 is 79809991.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 17631601 + 2359296 = 4199^2 + 1536^2 .

It is an emirp because it is prime and its reverse (79809991) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 19990897 - 2¹¹ = 19988849 is a prime.

It is not a weakly prime, because it can be changed into another prime (19990891) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 9995448 + 9995449.

It is an arithmetic number, because the mean of its divisors is an integer number (9995449).

Almost surely, 2^19990897 is an apocalyptic number.

It is an amenable number.

19990897 is a deficient number, since it is larger than the sum of its proper divisors (1).

19990897 is an equidigital number, since it uses as much as digits as its factorization.

19990897 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 367416, while the sum is 52.

The square root of 19990897 is about 4471.1180928264. The cubic root of 19990897 is about 271.4005731706.

The spelling of 19990897 in words is "nineteen million, nine hundred ninety thousand, eight hundred ninety-seven".