1820639813 has 2 divisors, whose sum is σ = 1820639814. Its totient is φ = 1820639812.

The previous prime is 1820639771. The next prime is 1820639833. The reversal of 1820639813 is 3189360281.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 1480864324 + 339775489 = 38482^2 + 18433^2 .

It is an emirp because it is prime and its reverse (3189360281) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 1820639813 - 2¹⁰ = 1820638789 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (1820639833) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 910319906 + 910319907.

It is an arithmetic number, because the mean of its divisors is an integer number (910319907).

Almost surely, 2^1820639813 is an apocalyptic number.

It is an amenable number.

1820639813 is a deficient number, since it is larger than the sum of its proper divisors (1).

1820639813 is an equidigital number, since it uses as much as digits as its factorization.

1820639813 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 62208, while the sum is 41.

The square root of 1820639813 is about 42668.9560805042. The cubic root of 1820639813 is about 1221.0722037434.

The spelling of 1820639813 in words is "one billion, eight hundred twenty million, six hundred thirty-nine thousand, eight hundred thirteen".