1990655993 has 2 divisors, whose sum is σ = 1990655994. Its totient is φ = 1990655992.

The previous prime is 1990655939. The next prime is 1990656007. The reversal of 1990655993 is 3995560991.

Together with previous prime (1990655939) it forms an Ormiston pair, because they use the same digits, order apart.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 1988892409 + 1763584 = 44597^2 + 1328^2 .

It is a cyclic number.

It is not a de Polignac number, because 1990655993 - 2¹⁰ = 1990654969 is a prime.

It is a super-2 number, since 2×1990655993² = 7925422564933632098, which contains 22 as substring.

It is a Sophie Germain prime.

It is a Curzon number.

It is not a weakly prime, because it can be changed into another prime (1990655923) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (23) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 995327996 + 995327997.

It is an arithmetic number, because the mean of its divisors is an integer number (995327997).

Almost surely, 2^1990655993 is an apocalyptic number.

It is an amenable number.

1990655993 is a deficient number, since it is larger than the sum of its proper divisors (1).

1990655993 is an equidigital number, since it uses as much as digits as its factorization.

1990655993 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 2952450, while the sum is 56.

The square root of 1990655993 is about 44616.7680698636. The cubic root of 1990655993 is about 1257.9558677458.

The spelling of 1990655993 in words is "one billion, nine hundred ninety million, six hundred fifty-five thousand, nine hundred ninety-three".