4991581 has 6 divisors (see below), whose sum is σ = 5806590. Its totient is φ = 4278456.

The previous prime is 4991573. The next prime is 4991587. The reversal of 4991581 is 1851994.

It can be written as a sum of positive squares in only one way, i.e., 3705625 + 1285956 = 1925^2 + 1134^2 .

It is not a de Polignac number, because 4991581 - 2³ = 4991573 is a prime.

It is a super-2 number, since 2×4991581² = 49831761759122, which contains 22 as substring.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 4991581.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (4991587) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 50886 + ... + 50983.

It is an arithmetic number, because the mean of its divisors is an integer number (967765).

Almost surely, 2^4991581 is an apocalyptic number.

It is an amenable number.

4991581 is a deficient number, since it is larger than the sum of its proper divisors (815009).

4991581 is a wasteful number, since it uses less digits than its factorization.

4991581 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 101883 (or 101876 counting only the distinct ones).

The product of its digits is 12960, while the sum is 37.

The square root of 4991581 is about 2234.1846387441. The cubic root of 4991581 is about 170.9015654995.

It can be divided in two parts, 499 and 1581, that added together give a triangular number (2080 = T₆₄).

The spelling of 4991581 in words is "four million, nine hundred ninety-one thousand, five hundred eighty-one".