19393981 has 2 divisors, whose sum is σ = 19393982. Its totient is φ = 19393980.

The previous prime is 19393961. The next prime is 19394027. The reversal of 19393981 is 18939391.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 14062500 + 5331481 = 3750^2 + 2309^2 .

It is a cyclic number.

It is not a de Polignac number, because 19393981 - 2¹³ = 19385789 is a prime.

It is a super-2 number, since 2×19393981² = 752252998056722, which contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (19393921) 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, 9696990 + 9696991.

It is an arithmetic number, because the mean of its divisors is an integer number (9696991).

Almost surely, 2^19393981 is an apocalyptic number.

It is an amenable number.

19393981 is a deficient number, since it is larger than the sum of its proper divisors (1).

19393981 is an equidigital number, since it uses as much as digits as its factorization.

19393981 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 52488, while the sum is 43.

The square root of 19393981 is about 4403.8597843256. The cubic root of 19393981 is about 268.6719466137.

The spelling of 19393981 in words is "nineteen million, three hundred ninety-three thousand, nine hundred eighty-one".