19261981 has 2 divisors, whose sum is σ = 19261982. Its totient is φ = 19261980.

The previous prime is 19261973. The next prime is 19261987. The reversal of 19261981 is 18916291.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 16402500 + 2859481 = 4050^2 + 1691^2 .

It is a cyclic number.

It is not a de Polignac number, because 19261981 - 2³ = 19261973 is a prime.

It is a super-2 number, since 2×19261981² = 742047824088722, which contains 22 as substring.

It is a self number, because there is not a number n which added to its sum of digits gives 19261981.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (19261987) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 9630990 + 9630991.

It is an arithmetic number, because the mean of its divisors is an integer number (9630991).

Almost surely, 2^19261981 is an apocalyptic number.

It is an amenable number.

19261981 is a deficient number, since it is larger than the sum of its proper divisors (1).

19261981 is an equidigital number, since it uses as much as digits as its factorization.

19261981 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 7776, while the sum is 37.

The square root of 19261981 is about 4388.8473429820. The cubic root of 19261981 is about 268.0610102801.

The spelling of 19261981 in words is "nineteen million, two hundred sixty-one thousand, nine hundred eighty-one".