19842391 has 2 divisors, whose sum is σ = 19842392. Its totient is φ = 19842390.

The previous prime is 19842379. The next prime is 19842443. The reversal of 19842391 is 19324891.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 19842391 - 2¹⁵ = 19809623 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 19842391.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (19842191) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 9921195 + 9921196.

It is an arithmetic number, because the mean of its divisors is an integer number (9921196).

Almost surely, 2^19842391 is an apocalyptic number.

19842391 is a deficient number, since it is larger than the sum of its proper divisors (1).

19842391 is an equidigital number, since it uses as much as digits as its factorization.

19842391 is an evil number, because the sum of its binary digits is even.

The product of its digits is 15552, while the sum is 37.

The square root of 19842391 is about 4454.4798798513. The cubic root of 19842391 is about 270.7268526794.

The spelling of 19842391 in words is "nineteen million, eight hundred forty-two thousand, three hundred ninety-one".