19509019261 has 2 divisors, whose sum is σ = 19509019262. Its totient is φ = 19509019260.

The previous prime is 19509019223. The next prime is 19509019319. The reversal of 19509019261 is 16291090591.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 10898107236 + 8610912025 = 104394^2 + 92795^2 .

It is an emirp because it is prime and its reverse (16291090591) is a distict prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-19509019261 is a prime.

It is a super-2 number, since 2×19509019261² (a number of 21 digits) contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (19509019661) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 9754509630 + 9754509631.

It is an arithmetic number, because the mean of its divisors is an integer number (9754509631).

Almost surely, 2^19509019261 is an apocalyptic number.

It is an amenable number.

19509019261 is a deficient number, since it is larger than the sum of its proper divisors (1).

19509019261 is an equidigital number, since it uses as much as digits as its factorization.

19509019261 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 43740, while the sum is 43.

The spelling of 19509019261 in words is "nineteen billion, five hundred nine million, nineteen thousand, two hundred sixty-one".