3999809985 has 16 divisors (see below), whose sum is σ = 6736522560. Its totient is φ = 2020956480.

The previous prime is 3999809939. The next prime is 3999809993. The reversal of 3999809985 is 5899089993.

It is not a de Polignac number, because 3999809985 - 2⁸ = 3999809729 is a prime.

It is a super-2 number, since 2×3999809985² = 31996959832211400450, which contains 22 as substring.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 7016926 + ... + 7017495.

It is an arithmetic number, because the mean of its divisors is an integer number (421032660).

Almost surely, 2^3999809985 is an apocalyptic number.

It is an amenable number.

3999809985 is a deficient number, since it is larger than the sum of its proper divisors (2736712575).

3999809985 is a wasteful number, since it uses less digits than its factorization.

3999809985 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 14034448.

The product of its (nonzero) digits is 56687040, while the sum is 69.

The square root of 3999809985 is about 63244.0509850531. The cubic root of 3999809985 is about 1587.3759157359.

It can be divided in two parts, 399980 and 9985, that added together give a triangular number (409965 = T₉₀₅).

The spelling of 3999809985 in words is "three billion, nine hundred ninety-nine million, eight hundred nine thousand, nine hundred eighty-five".