3999561 has 8 divisors (see below), whose sum is σ = 5373984. Its totient is φ = 2645760.

The previous prime is 3999547. The next prime is 3999563. The reversal of 3999561 is 1659993.

3999561 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 3999561 - 2⁵ = 3999529 is a prime.

3999561 is a lucky number.

It is not an unprimeable number, because it can be changed into a prime (3999563) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 4696 + ... + 5481.

It is an arithmetic number, because the mean of its divisors is an integer number (671748).

Almost surely, 2^3999561 is an apocalyptic number.

It is an amenable number.

3999561 is a deficient number, since it is larger than the sum of its proper divisors (1374423).

3999561 is a wasteful number, since it uses less digits than its factorization.

3999561 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 10311.

The product of its digits is 65610, while the sum is 42.

The square root of 3999561 is about 1999.8902469886. The cubic root of 3999561 is about 158.7342977422.

It can be divided in two parts, 3999 and 561, that added together give a triangular number (4560 = T₉₅).

The spelling of 3999561 in words is "three million, nine hundred ninety-nine thousand, five hundred sixty-one".