3991399 has 2 divisors, whose sum is σ = 3991400. Its totient is φ = 3991398.

The previous prime is 3991369. The next prime is 3991441. The reversal of 3991399 is 9931993.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 3991399 - 2¹¹ = 3989351 is a prime.

It is a nialpdrome in base 13.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (3991369) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 1995699 + 1995700.

It is an arithmetic number, because the mean of its divisors is an integer number (1995700).

Almost surely, 2^3991399 is an apocalyptic number.

3991399 is a deficient number, since it is larger than the sum of its proper divisors (1).

3991399 is an equidigital number, since it uses as much as digits as its factorization.

3991399 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 59049, while the sum is 43.

The square root of 3991399 is about 1997.8485928618. The cubic root of 3991399 is about 158.6262465792.

The spelling of 3991399 in words is "three million, nine hundred ninety-one thousand, three hundred ninety-nine".