3866991 has 4 divisors (see below), whose sum is σ = 5155992. Its totient is φ = 2577992.

The previous prime is 3866983. The next prime is 3867001. The reversal of 3866991 is 1996683.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 3866991 - 2³ = 3866983 is a prime.

It is a D-number.

3866991 is a lucky number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (3866911) 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, 644496 + ... + 644501.

It is an arithmetic number, because the mean of its divisors is an integer number (1288998).

Almost surely, 2^3866991 is an apocalyptic number.

3866991 is a deficient number, since it is larger than the sum of its proper divisors (1289001).

3866991 is a wasteful number, since it uses less digits than its factorization.

3866991 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1289000.

The product of its digits is 69984, while the sum is 42.

The square root of 3866991 is about 1966.4666282447. The cubic root of 3866991 is about 156.9607458626.

The spelling of 3866991 in words is "three million, eight hundred sixty-six thousand, nine hundred ninety-one".