2561999819 has 2 divisors, whose sum is σ = 2561999820. Its totient is φ = 2561999818.

The previous prime is 2561999789. The next prime is 2561999821. The reversal of 2561999819 is 9189991652.

It is a strong prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-2561999819 is a prime.

It is a super-2 number, since 2×2561999819² = 13127686145112065522, which contains 22 as substring.

Together with 2561999821, it forms a pair of twin primes.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (2561999879) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 1280999909 + 1280999910.

It is an arithmetic number, because the mean of its divisors is an integer number (1280999910).

Almost surely, 2^2561999819 is an apocalyptic number.

2561999819 is a deficient number, since it is larger than the sum of its proper divisors (1).

2561999819 is an equidigital number, since it uses as much as digits as its factorization.

2561999819 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 3149280, while the sum is 59.

The square root of 2561999819 is about 50616.2011514100. The cubic root of 2561999819 is about 1368.3368773750.

The spelling of 2561999819 in words is "two billion, five hundred sixty-one million, nine hundred ninety-nine thousand, eight hundred nineteen".