2491921 has 4 divisors (see below), whose sum is σ = 2495344. Its totient is φ = 2488500.

The previous prime is 2491903. The next prime is 2491933. The reversal of 2491921 is 1291942.

It is a happy number.

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 2491921 - 2¹¹ = 2489873 is a prime.

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 2491921.

It is not an unprimeable number, because it can be changed into a prime (2491961) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (7) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 135 + ... + 2236.

It is an arithmetic number, because the mean of its divisors is an integer number (623836).

2^2491921 is an apocalyptic number.

It is an amenable number.

2491921 is a deficient number, since it is larger than the sum of its proper divisors (3423).

2491921 is a wasteful number, since it uses less digits than its factorization.

2491921 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3422.

The product of its digits is 1296, while the sum is 28.

The square root of 2491921 is about 1578.5819585945. The cubic root of 2491921 is about 135.5745245285.

The spelling of 2491921 in words is "two million, four hundred ninety-one thousand, nine hundred twenty-one".