819864641 has 2 divisors, whose sum is σ = 819864642. Its totient is φ = 819864640.

The previous prime is 819864637. The next prime is 819864667. The reversal of 819864641 is 146468918.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 795014416 + 24850225 = 28196^2 + 4985^2 .

It is a cyclic number.

It is not a de Polignac number, because 819864641 - 2² = 819864637 is a prime.

It is not a weakly prime, because it can be changed into another prime (819864691) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 409932320 + 409932321.

It is an arithmetic number, because the mean of its divisors is an integer number (409932321).

Almost surely, 2^819864641 is an apocalyptic number.

It is an amenable number.

819864641 is a deficient number, since it is larger than the sum of its proper divisors (1).

819864641 is an equidigital number, since it uses as much as digits as its factorization.

819864641 is an evil number, because the sum of its binary digits is even.

The product of its digits is 331776, while the sum is 47.

The square root of 819864641 is about 28633.2785583489. The cubic root of 819864641 is about 935.9386575725.

The spelling of 819864641 in words is "eight hundred nineteen million, eight hundred sixty-four thousand, six hundred forty-one".