2566721 has 4 divisors (see below), whose sum is σ = 2602944. Its totient is φ = 2530500.

The previous prime is 2566709. The next prime is 2566747. The reversal of 2566721 is 1276652.

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.

It is a cyclic number.

It is not a de Polignac number, because 2566721 - 2¹⁴ = 2550337 is a prime.

It is a d-powerful number, because it can be written as 2⁸ + 5⁶ + 6⁶ + 6⁸ + 7⁷ + 2¹⁰ + 1 .

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (2566771) 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, 18005 + ... + 18146.

It is an arithmetic number, because the mean of its divisors is an integer number (650736).

2^2566721 is an apocalyptic number.

It is an amenable number.

2566721 is a deficient number, since it is larger than the sum of its proper divisors (36223).

2566721 is an equidigital number, since it uses as much as digits as its factorization.

2566721 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 36222.

The product of its digits is 5040, while the sum is 29.

The square root of 2566721 is about 1602.0989357714. The cubic root of 2566721 is about 136.9176872480.

The spelling of 2566721 in words is "two million, five hundred sixty-six thousand, seven hundred twenty-one".