19957009 has 2 divisors, whose sum is σ = 19957010. Its totient is φ = 19957008.

The previous prime is 19956961. The next prime is 19957033. The reversal of 19957009 is 90075991.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 13300609 + 6656400 = 3647^2 + 2580^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-19957009 is a prime.

It is not a weakly prime, because it can be changed into another prime (19957039) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 9978504 + 9978505.

It is an arithmetic number, because the mean of its divisors is an integer number (9978505).

Almost surely, 2^19957009 is an apocalyptic number.

It is an amenable number.

19957009 is a deficient number, since it is larger than the sum of its proper divisors (1).

19957009 is an equidigital number, since it uses as much as digits as its factorization.

19957009 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 25515, while the sum is 40.

The square root of 19957009 is about 4467.3268293242. The cubic root of 19957009 is about 271.2471295894.

The spelling of 19957009 in words is "nineteen million, nine hundred fifty-seven thousand, nine".