19890961 has 2 divisors, whose sum is σ = 19890962. Its totient is φ = 19890960.

The previous prime is 19890919. The next prime is 19890973. The reversal of 19890961 is 16909891.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 12383361 + 7507600 = 3519^2 + 2740^2 .

It is an emirp because it is prime and its reverse (16909891) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 19890961 - 2⁹ = 19890449 is a prime.

It is not a weakly prime, because it can be changed into another prime (19890911) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 9945480 + 9945481.

It is an arithmetic number, because the mean of its divisors is an integer number (9945481).

Almost surely, 2^19890961 is an apocalyptic number.

It is an amenable number.

19890961 is a deficient number, since it is larger than the sum of its proper divisors (1).

19890961 is an equidigital number, since it uses as much as digits as its factorization.

19890961 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 34992, while the sum is 43.

The square root of 19890961 is about 4459.9283626534. The cubic root of 19890961 is about 270.9475668224.

The spelling of 19890961 in words is "nineteen million, eight hundred ninety thousand, nine hundred sixty-one".