1985555281 has 2 divisors, whose sum is σ = 1985555282. Its totient is φ = 1985555280.

The previous prime is 1985555249. The next prime is 1985555287. The reversal of 1985555281 is 1825555891.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 1643897025 + 341658256 = 40545^2 + 18484^2 .

It is a cyclic number.

It is not a de Polignac number, because 1985555281 - 2⁵ = 1985555249 is a prime.

It is a super-2 number, since 2×1985555281² = 7884859547813977922, which contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (1985555287) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 992777640 + 992777641.

It is an arithmetic number, because the mean of its divisors is an integer number (992777641).

Almost surely, 2^1985555281 is an apocalyptic number.

It is an amenable number.

1985555281 is a deficient number, since it is larger than the sum of its proper divisors (1).

1985555281 is an equidigital number, since it uses as much as digits as its factorization.

1985555281 is an evil number, because the sum of its binary digits is even.

The product of its digits is 720000, while the sum is 49.

The square root of 1985555281 is about 44559.5700270997. The cubic root of 1985555281 is about 1256.8805172427.

The spelling of 1985555281 in words is "one billion, nine hundred eighty-five million, five hundred fifty-five thousand, two hundred eighty-one".