3999639 has 16 divisors (see below), whose sum is σ = 6125312. Its totient is φ = 2274048.

The previous prime is 3999637. The next prime is 3999647. The reversal of 3999639 is 9369993.

It is not a de Polignac number, because 3999639 - 2¹ = 3999637 is a prime.

It is a super-2 number, since 2×3999639² = 31994224260642, which contains 22 as substring.

It is a Duffinian number.

3999639 is a lucky number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (3999637) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 5607 + ... + 6279.

It is an arithmetic number, because the mean of its divisors is an integer number (382832).

Almost surely, 2^3999639 is an apocalyptic number.

3999639 is a deficient number, since it is larger than the sum of its proper divisors (2125673).

3999639 is a wasteful number, since it uses less digits than its factorization.

3999639 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 966.

The product of its digits is 354294, while the sum is 48.

The square root of 3999639 is about 1999.9097479636. The cubic root of 3999639 is about 158.7353296217.

The spelling of 3999639 in words is "three million, nine hundred ninety-nine thousand, six hundred thirty-nine".