19611881 has 2 divisors, whose sum is σ = 19611882. Its totient is φ = 19611880.

The previous prime is 19611803. The next prime is 19611883. The reversal of 19611881 is 18811691.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 15531481 + 4080400 = 3941^2 + 2020^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-19611881 is a prime.

It is a super-2 number, since 2×19611881² = 769251752716322, which contains 22 as substring.

Together with 19611883, 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 (19611883) 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, 9805940 + 9805941.

It is an arithmetic number, because the mean of its divisors is an integer number (9805941).

Almost surely, 2^19611881 is an apocalyptic number.

It is an amenable number.

19611881 is a deficient number, since it is larger than the sum of its proper divisors (1).

19611881 is an equidigital number, since it uses as much as digits as its factorization.

19611881 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 3456, while the sum is 35.

The square root of 19611881 is about 4428.5303431274. The cubic root of 19611881 is about 269.6744177936.

It can be divided in two parts, 196 and 11881, that multiplied together give a square (2328676 = 1526²).

The spelling of 19611881 in words is "nineteen million, six hundred eleven thousand, eight hundred eighty-one".