19891541 has 2 divisors, whose sum is σ = 19891542. Its totient is φ = 19891540.

The previous prime is 19891523. The next prime is 19891549. The reversal of 19891541 is 14519891.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 15602500 + 4289041 = 3950^2 + 2071^2 .

It is a cyclic number.

It is not a de Polignac number, because 19891541 - 2¹⁰ = 19890517 is a prime.

It is a Sophie Germain prime.

It is a Curzon number.

It is a junction number, because it is equal to n+sod(n) for n = 19891495 and 19891504.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (19891549) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 9945770 + 9945771.

It is an arithmetic number, because the mean of its divisors is an integer number (9945771).

Almost surely, 2^19891541 is an apocalyptic number.

It is an amenable number.

19891541 is a deficient number, since it is larger than the sum of its proper divisors (1).

19891541 is an equidigital number, since it uses as much as digits as its factorization.

19891541 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 12960, while the sum is 38.

The square root of 19891541 is about 4459.9933856453. The cubic root of 19891541 is about 270.9502003144.

The spelling of 19891541 in words is "nineteen million, eight hundred ninety-one thousand, five hundred forty-one".