3951999 has 12 divisors (see below), whose sum is σ = 5729776. Its totient is φ = 2624832.

The previous prime is 3951989. The next prime is 3952009. The reversal of 3951999 is 9991593.

It is an interprime number because it is at equal distance from previous prime (3951989) and next prime (3952009).

It is not a de Polignac number, because 3951999 - 2⁵ = 3951967 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 (3951989) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 2382 + ... + 3684.

Almost surely, 2^3951999 is an apocalyptic number.

3951999 is a deficient number, since it is larger than the sum of its proper divisors (1777777).

3951999 is a wasteful number, since it uses less digits than its factorization.

3951999 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1646 (or 1643 counting only the distinct ones).

The product of its digits is 98415, while the sum is 45.

The square root of 3951999 is about 1987.9635308526. The cubic root of 3951999 is about 158.1025745302.

It can be divided in two parts, 3951 and 999, that added together give a triangular number (4950 = T₉₉).

The spelling of 3951999 in words is "three million, nine hundred fifty-one thousand, nine hundred ninety-nine".