19943256497 has 2 divisors, whose sum is σ = 19943256498. Its totient is φ = 19943256496.

The previous prime is 19943256479. The next prime is 19943256511. The reversal of 19943256497 is 79465234991.

Together with previous prime (19943256479) it forms an Ormiston pair, because they use the same digits, order apart.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 18116890801 + 1826365696 = 134599^2 + 42736^2 .

It is a cyclic number.

It is not a de Polignac number, because 19943256497 - 2¹⁰ = 19943255473 is a prime.

It is a super-2 number, since 2×19943256497² (a number of 21 digits) contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (19943256407) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 9971628248 + 9971628249.

It is an arithmetic number, because the mean of its divisors is an integer number (9971628249).

Almost surely, 2^19943256497 is an apocalyptic number.

It is an amenable number.

19943256497 is a deficient number, since it is larger than the sum of its proper divisors (1).

19943256497 is an equidigital number, since it uses as much as digits as its factorization.

19943256497 is an evil number, because the sum of its binary digits is even.

The product of its digits is 14696640, while the sum is 59.

The spelling of 19943256497 in words is "nineteen billion, nine hundred forty-three million, two hundred fifty-six thousand, four hundred ninety-seven".