19921773281 has 2 divisors, whose sum is σ = 19921773282. Its totient is φ = 19921773280.

The previous prime is 19921773253. The next prime is 19921773331. The reversal of 19921773281 is 18237712991.

It is an a-pointer prime, because the next prime (19921773331) can be obtained adding 19921773281 to its sum of digits (50).

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 15032966881 + 4888806400 = 122609^2 + 69920^2 .

It is a cyclic number.

It is not a de Polignac number, because 19921773281 - 2⁶ = 19921773217 is a prime.

It is a super-2 number, since 2×19921773281² (a number of 21 digits) contains 22 as substring.

It is a Sophie Germain prime.

It is a Curzon number.

It is not a weakly prime, because it can be changed into another prime (19921773241) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 9960886640 + 9960886641.

It is an arithmetic number, because the mean of its divisors is an integer number (9960886641).

Almost surely, 2^19921773281 is an apocalyptic number.

It is an amenable number.

19921773281 is a deficient number, since it is larger than the sum of its proper divisors (1).

19921773281 is an equidigital number, since it uses as much as digits as its factorization.

19921773281 is an evil number, because the sum of its binary digits is even.

The product of its digits is 381024, while the sum is 50.

The spelling of 19921773281 in words is "nineteen billion, nine hundred twenty-one million, seven hundred seventy-three thousand, two hundred eighty-one".