4018991 has 4 divisors (see below), whose sum is σ = 4024512. Its totient is φ = 4013472.

The previous prime is 4018981. The next prime is 4019003. The reversal of 4018991 is 1998104.

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

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-4018991 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 (4018901) 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, 1466 + ... + 3191.

It is an arithmetic number, because the mean of its divisors is an integer number (1006128).

Almost surely, 2^4018991 is an apocalyptic number.

4018991 is a deficient number, since it is larger than the sum of its proper divisors (5521).

4018991 is an equidigital number, since it uses as much as digits as its factorization.

4018991 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 5520.

The product of its (nonzero) digits is 2592, while the sum is 32.

The square root of 4018991 is about 2004.7421280554. The cubic root of 4018991 is about 158.9909281113.

The spelling of 4018991 in words is "four million, eighteen thousand, nine hundred ninety-one".