19839997 has 2 divisors, whose sum is σ = 19839998. Its totient is φ = 19839996.

The previous prime is 19839991. The next prime is 19840019. The reversal of 19839997 is 79993891.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 18714276 + 1125721 = 4326^2 + 1061^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-19839997 is a prime.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (19839991) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 9919998 + 9919999.

It is an arithmetic number, because the mean of its divisors is an integer number (9919999).

Almost surely, 2^19839997 is an apocalyptic number.

It is an amenable number.

19839997 is a deficient number, since it is larger than the sum of its proper divisors (1).

19839997 is an equidigital number, since it uses as much as digits as its factorization.

19839997 is an evil number, because the sum of its binary digits is even.

The product of its digits is 1102248, while the sum is 55.

The square root of 19839997 is about 4454.2111535041. The cubic root of 19839997 is about 270.7159644393.

The spelling of 19839997 in words is "nineteen million, eight hundred thirty-nine thousand, nine hundred ninety-seven".