19684981 has 2 divisors, whose sum is σ = 19684982. Its totient is φ = 19684980.

The previous prime is 19684967. The next prime is 19684991. The reversal of 19684981 is 18948691.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 10504081 + 9180900 = 3241^2 + 3030^2 .

It is an emirp because it is prime and its reverse (18948691) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 19684981 - 2⁵ = 19684949 is a prime.

It is a super-2 number, since 2×19684981² = 774996953940722, which contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (19684991) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 9842490 + 9842491.

It is an arithmetic number, because the mean of its divisors is an integer number (9842491).

Almost surely, 2^19684981 is an apocalyptic number.

It is an amenable number.

19684981 is a deficient number, since it is larger than the sum of its proper divisors (1).

19684981 is an equidigital number, since it uses as much as digits as its factorization.

19684981 is an evil number, because the sum of its binary digits is even.

The product of its digits is 124416, while the sum is 46.

The square root of 19684981 is about 4436.7759691019. The cubic root of 19684981 is about 270.0090577665.

The spelling of 19684981 in words is "nineteen million, six hundred eighty-four thousand, nine hundred eighty-one".