819147923021 has 2 divisors, whose sum is σ = 819147923022. Its totient is φ = 819147923020.

The previous prime is 819147922993. The next prime is 819147923173. The reversal of 819147923021 is 120329741918.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 536682247396 + 282465675625 = 732586^2 + 531475^2 .

It is a cyclic number.

It is not a de Polignac number, because 819147923021 - 2¹⁰ = 819147921997 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (819147923821) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 409573961510 + 409573961511.

It is an arithmetic number, because the mean of its divisors is an integer number (409573961511).

Almost surely, 2^819147923021 is an apocalyptic number.

It is an amenable number.

819147923021 is a deficient number, since it is larger than the sum of its proper divisors (1).

819147923021 is an equidigital number, since it uses as much as digits as its factorization.

819147923021 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 217728, while the sum is 47.

The spelling of 819147923021 in words is "eight hundred nineteen billion, one hundred forty-seven million, nine hundred twenty-three thousand, twenty-one".