3999961 has 8 divisors (see below), whose sum is σ = 4719104. Its totient is φ = 3317760.

The previous prime is 3999949. The next prime is 3999971. The reversal of 3999961 is 1699993.

3999961 = T₇₃ + T₇₄ + ... + T₂₈₉.

3999961 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 a 5-Lehmer number, since φ(3999961) divides (3999961-1)⁵.

It is a cyclic number.

It is not a de Polignac number, because 3999961 - 2⁵ = 3999929 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (3999901) 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, 9000 + ... + 9433.

It is an arithmetic number, because the mean of its divisors is an integer number (589888).

Almost surely, 2^3999961 is an apocalyptic number.

3999961 is a gapful number since it is divisible by the number (31) formed by its first and last digit.

It is an amenable number.

3999961 is a deficient number, since it is larger than the sum of its proper divisors (719143).

3999961 is a wasteful number, since it uses less digits than its factorization.

3999961 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 18471.

The product of its digits is 118098, while the sum is 46.

The square root of 3999961 is about 1999.9902499762. The cubic root of 3999961 is about 158.7395892898.

Subtracting from 3999961 its reverse (1699993), we obtain a cube (2299968 = 132³).

It can be divided in two parts, 39 and 99961, that added together give a 5-th power (100000 = 10⁵).

The spelling of 3999961 in words is "three million, nine hundred ninety-nine thousand, nine hundred sixty-one".