19957409 has 2 divisors, whose sum is σ = 19957410. Its totient is φ = 19957408.

The previous prime is 19957387. The next prime is 19957411. The reversal of 19957409 is 90475991.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 12229009 + 7728400 = 3497^2 + 2780^2 .

It is a cyclic number.

It is not a de Polignac number, because 19957409 - 2⁸ = 19957153 is a prime.

Together with 19957411, it forms a pair of twin primes.

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 19957409.

It is not a weakly prime, because it can be changed into another prime (19957009) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 9978704 + 9978705.

It is an arithmetic number, because the mean of its divisors is an integer number (9978705).

Almost surely, 2^19957409 is an apocalyptic number.

It is an amenable number.

19957409 is a deficient number, since it is larger than the sum of its proper divisors (1).

19957409 is an equidigital number, since it uses as much as digits as its factorization.

19957409 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 102060, while the sum is 44.

The square root of 19957409 is about 4467.3715986025. The cubic root of 19957409 is about 271.2489417869.

The spelling of 19957409 in words is "nineteen million, nine hundred fifty-seven thousand, four hundred nine".