19915897 has 2 divisors, whose sum is σ = 19915898. Its totient is φ = 19915896.

The previous prime is 19915871. The next prime is 19915949. The reversal of 19915897 is 79851991.

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., 19900521 + 15376 = 4461^2 + 124^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-19915897 is a prime.

It is a Chen prime.

It is a self number, because there is not a number n which added to its sum of digits gives 19915897.

It is not a weakly prime, because it can be changed into another prime (19915807) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 9957948 + 9957949.

It is an arithmetic number, because the mean of its divisors is an integer number (9957949).

Almost surely, 2^19915897 is an apocalyptic number.

It is an amenable number.

19915897 is a deficient number, since it is larger than the sum of its proper divisors (1).

19915897 is an equidigital number, since it uses as much as digits as its factorization.

19915897 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 204120, while the sum is 49.

The square root of 19915897 is about 4462.7230476470. The cubic root of 19915897 is about 271.0607426373.

The spelling of 19915897 in words is "nineteen million, nine hundred fifteen thousand, eight hundred ninety-seven".