19864637381 has 2 divisors, whose sum is σ = 19864637382. Its totient is φ = 19864637380.

The previous prime is 19864637347. The next prime is 19864637393. The reversal of 19864637381 is 18373646891.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 19653516481 + 211120900 = 140191^2 + 14530^2 .

It is an emirp because it is prime and its reverse (18373646891) is a distict prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-19864637381 is a prime.

It is a super-2 number, since 2×19864637381² (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 (19864630381) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 9932318690 + 9932318691.

It is an arithmetic number, because the mean of its divisors is an integer number (9932318691).

Almost surely, 2^19864637381 is an apocalyptic number.

It is an amenable number.

19864637381 is a deficient number, since it is larger than the sum of its proper divisors (1).

19864637381 is an equidigital number, since it uses as much as digits as its factorization.

19864637381 is an evil number, because the sum of its binary digits is even.

The product of its digits is 5225472, while the sum is 56.

The spelling of 19864637381 in words is "nineteen billion, eight hundred sixty-four million, six hundred thirty-seven thousand, three hundred eighty-one".