3961991 has 4 divisors (see below), whose sum is σ = 4322184. Its totient is φ = 3601800.

The previous prime is 3961987. The next prime is 3962029. The reversal of 3961991 is 1991693.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 1991693 = 11 ⋅181063.

It is a cyclic number.

It is not a de Polignac number, because 3961991 - 2² = 3961987 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 (3961961) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 180080 + ... + 180101.

It is an arithmetic number, because the mean of its divisors is an integer number (1080546).

Almost surely, 2^3961991 is an apocalyptic number.

3961991 is a deficient number, since it is larger than the sum of its proper divisors (360193).

3961991 is a wasteful number, since it uses less digits than its factorization.

3961991 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 360192.

The product of its digits is 13122, while the sum is 38.

The square root of 3961991 is about 1990.4750689220. The cubic root of 3961991 is about 158.2357081165.

The spelling of 3961991 in words is "three million, nine hundred sixty-one thousand, nine hundred ninety-one".