1990859621 has 2 divisors, whose sum is σ = 1990859622. Its totient is φ = 1990859620.

The previous prime is 1990859593. The next prime is 1990859627. The reversal of 1990859621 is 1269580991.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 1669948225 + 320911396 = 40865^2 + 17914^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-1990859621 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 1990859621.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (1990859627) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 995429810 + 995429811.

It is an arithmetic number, because the mean of its divisors is an integer number (995429811).

Almost surely, 2^1990859621 is an apocalyptic number.

It is an amenable number.

1990859621 is a deficient number, since it is larger than the sum of its proper divisors (1).

1990859621 is an equidigital number, since it uses as much as digits as its factorization.

1990859621 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 349920, while the sum is 50.

The square root of 1990859621 is about 44619.0499786806. The cubic root of 1990859621 is about 1257.9987591853.

The spelling of 1990859621 in words is "one billion, nine hundred ninety million, eight hundred fifty-nine thousand, six hundred twenty-one".