4891561 has 4 divisors (see below), whose sum is σ = 4896000. Its totient is φ = 4887124.

The previous prime is 4891559. The next prime is 4891567. The reversal of 4891561 is 1651984.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4, and also a brilliant number, because the two primes have the same length.

It is a cyclic number.

It is not a de Polignac number, because 4891561 - 2¹ = 4891559 is a prime.

It is a Duffinian number.

4891561 is a lucky number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (4891567) 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 3 ways as a sum of consecutive naturals, for example, 840 + ... + 3238.

It is an arithmetic number, because the mean of its divisors is an integer number (1224000).

Almost surely, 2^4891561 is an apocalyptic number.

It is an amenable number.

4891561 is a deficient number, since it is larger than the sum of its proper divisors (4439).

4891561 is a wasteful number, since it uses less digits than its factorization.

4891561 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4438.

The product of its digits is 8640, while the sum is 34.

The square root of 4891561 is about 2211.6873648868. The cubic root of 4891561 is about 169.7523614708.

The spelling of 4891561 in words is "four million, eight hundred ninety-one thousand, five hundred sixty-one".