1990746581 has 2 divisors, whose sum is σ = 1990746582. Its totient is φ = 1990746580.

The previous prime is 1990746551. The next prime is 1990746613. The reversal of 1990746581 is 1856470991.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 1312612900 + 678133681 = 36230^2 + 26041^2 .

It is a cyclic number.

It is not a de Polignac number, because 1990746581 - 2¹⁰ = 1990745557 is a prime.

It is a super-2 number, since 2×1990746581² = 7926143899526379122, which contains 22 as substring.

It is a Sophie Germain prime.

It is a Curzon number.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (1990746521) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 995373290 + 995373291.

It is an arithmetic number, because the mean of its divisors is an integer number (995373291).

Almost surely, 2^1990746581 is an apocalyptic number.

It is an amenable number.

1990746581 is a deficient number, since it is larger than the sum of its proper divisors (1).

1990746581 is an equidigital number, since it uses as much as digits as its factorization.

1990746581 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 544320, while the sum is 50.

The square root of 1990746581 is about 44617.7832371802. The cubic root of 1990746581 is about 1257.9749492241.

The spelling of 1990746581 in words is "one billion, nine hundred ninety million, seven hundred forty-six thousand, five hundred eighty-one".