1985109851 has 2 divisors, whose sum is σ = 1985109852. Its totient is φ = 1985109850.

The previous prime is 1985109817. The next prime is 1985109869. The reversal of 1985109851 is 1589015891.

It is a strong prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-1985109851 is a prime.

It is a super-2 number, since 2×1985109851² = 7881322241074484402, which contains 22 as substring.

It is a Sophie Germain prime.

It is a junction number, because it is equal to n+sod(n) for n = 1985109796 and 1985109805.

It is not a weakly prime, because it can be changed into another prime (1985109871) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 992554925 + 992554926.

It is an arithmetic number, because the mean of its divisors is an integer number (992554926).

Almost surely, 2^1985109851 is an apocalyptic number.

1985109851 is a deficient number, since it is larger than the sum of its proper divisors (1).

1985109851 is an equidigital number, since it uses as much as digits as its factorization.

1985109851 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 129600, while the sum is 47.

The square root of 1985109851 is about 44554.5716060653. The cubic root of 1985109851 is about 1256.7865226871.

The spelling of 1985109851 in words is "one billion, nine hundred eighty-five million, one hundred nine thousand, eight hundred fifty-one".