19957000981 has 2 divisors, whose sum is σ = 19957000982. Its totient is φ = 19957000980.

The previous prime is 19957000933. The next prime is 19957000997. The reversal of 19957000981 is 18900075991.

It is a happy number.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 19267938481 + 689062500 = 138809^2 + 26250^2 .

It is an emirp because it is prime and its reverse (18900075991) is a distict prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-19957000981 is a prime.

It is a super-2 number, since 2×19957000981² (a number of 21 digits) contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (19957000901) 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, 9978500490 + 9978500491.

It is an arithmetic number, because the mean of its divisors is an integer number (9978500491).

Almost surely, 2^19957000981 is an apocalyptic number.

It is an amenable number.

19957000981 is a deficient number, since it is larger than the sum of its proper divisors (1).

19957000981 is an equidigital number, since it uses as much as digits as its factorization.

19957000981 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 204120, while the sum is 49.

The spelling of 19957000981 in words is "nineteen billion, nine hundred fifty-seven million, nine hundred eighty-one", and thus it is an aban number.