19491881 has 2 divisors, whose sum is σ = 19491882. Its totient is φ = 19491880.

The previous prime is 19491827. The next prime is 19491893. The reversal of 19491881 is 18819491.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 16736281 + 2755600 = 4091^2 + 1660^2 .

It is a cyclic number.

It is not a de Polignac number, because 19491881 - 2⁶ = 19491817 is a prime.

It is a super-2 number, since 2×19491881² = 759866849836322, which contains 22 as substring.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (19491811) 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, 9745940 + 9745941.

It is an arithmetic number, because the mean of its divisors is an integer number (9745941).

Almost surely, 2^19491881 is an apocalyptic number.

It is an amenable number.

19491881 is a deficient number, since it is larger than the sum of its proper divisors (1).

19491881 is an equidigital number, since it uses as much as digits as its factorization.

19491881 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 20736, while the sum is 41.

The square root of 19491881 is about 4414.9610417307. The cubic root of 19491881 is about 269.1232696040.

The spelling of 19491881 in words is "nineteen million, four hundred ninety-one thousand, eight hundred eighty-one".