2505721 has 4 divisors (see below), whose sum is σ = 2509200. Its totient is φ = 2502244.

The previous prime is 2505707. The next prime is 2505743. The reversal of 2505721 is 1275052.

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 2505721 - 2¹⁷ = 2374649 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 2505692 and 2505701.

It is not an unprimeable number, because it can be changed into a prime (2505791) 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, 211 + ... + 2248.

It is an arithmetic number, because the mean of its divisors is an integer number (627300).

2^2505721 is an apocalyptic number.

It is an amenable number.

2505721 is a deficient number, since it is larger than the sum of its proper divisors (3479).

2505721 is a wasteful number, since it uses less digits than its factorization.

2505721 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3478.

The product of its (nonzero) digits is 700, while the sum is 22.

The square root of 2505721 is about 1582.9469353077. The cubic root of 2505721 is about 135.8243298468.

The spelling of 2505721 in words is "two million, five hundred five thousand, seven hundred twenty-one".