19089871721 has 2 divisors, whose sum is σ = 19089871722. Its totient is φ = 19089871720.

The previous prime is 19089871663. The next prime is 19089871739. The reversal of 19089871721 is 12717898091.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 18323412496 + 766459225 = 135364^2 + 27685^2 .

It is a cyclic number.

It is not a de Polignac number, because 19089871721 - 2⁶ = 19089871657 is a prime.

It is not a weakly prime, because it can be changed into another prime (19089871741) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 9544935860 + 9544935861.

It is an arithmetic number, because the mean of its divisors is an integer number (9544935861).

Almost surely, 2^19089871721 is an apocalyptic number.

It is an amenable number.

19089871721 is a deficient number, since it is larger than the sum of its proper divisors (1).

19089871721 is an equidigital number, since it uses as much as digits as its factorization.

19089871721 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 508032, while the sum is 53.

The spelling of 19089871721 in words is "nineteen billion, eighty-nine million, eight hundred seventy-one thousand, seven hundred twenty-one".