3991279 has 2 divisors, whose sum is σ = 3991280. Its totient is φ = 3991278.

The previous prime is 3991261. The next prime is 3991289. The reversal of 3991279 is 9721993.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 3991279 - 2²¹ = 1894127 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (3991289) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 1995639 + 1995640.

It is an arithmetic number, because the mean of its divisors is an integer number (1995640).

Almost surely, 2^3991279 is an apocalyptic number.

3991279 is a deficient number, since it is larger than the sum of its proper divisors (1).

3991279 is an equidigital number, since it uses as much as digits as its factorization.

3991279 is an evil number, because the sum of its binary digits is even.

The product of its digits is 30618, while the sum is 40.

The square root of 3991279 is about 1997.8185603302. The cubic root of 3991279 is about 158.6246568826.

The spelling of 3991279 in words is "three million, nine hundred ninety-one thousand, two hundred seventy-nine".