1990852781 has 2 divisors, whose sum is σ = 1990852782. Its totient is φ = 1990852780.

The previous prime is 1990852769. The next prime is 1990852817. The reversal of 1990852781 is 1872580991.

Together with next prime (1990852817) it forms an Ormiston pair, because they use the same digits, order apart.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 1924576900 + 66275881 = 43870^2 + 8141^2 .

It is a cyclic number.

It is not a de Polignac number, because 1990852781 - 2¹⁰ = 1990851757 is a prime.

It is a super-3 number, since 3×1990852781³ (a number of 29 digits) contains 333 as substring. Note that it is a super-d number also for d = 2.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (1990852741) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 995426390 + 995426391.

It is an arithmetic number, because the mean of its divisors is an integer number (995426391).

Almost surely, 2^1990852781 is an apocalyptic number.

It is an amenable number.

1990852781 is a deficient number, since it is larger than the sum of its proper divisors (1).

1990852781 is an equidigital number, since it uses as much as digits as its factorization.

1990852781 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 362880, while the sum is 50.

The square root of 1990852781 is about 44618.9733297394. The cubic root of 1990852781 is about 1257.9973184808.

The spelling of 1990852781 in words is "one billion, nine hundred ninety million, eight hundred fifty-two thousand, seven hundred eighty-one".