2505661 has 4 divisors (see below), whose sum is σ = 2541024. Its totient is φ = 2470300.

The previous prime is 2505641. The next prime is 2505673. The reversal of 2505661 is 1665052.

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 2505661 - 2⁷ = 2505533 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (2505611) 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, 17575 + ... + 17716.

It is an arithmetic number, because the mean of its divisors is an integer number (635256).

2^2505661 is an apocalyptic number.

It is an amenable number.

2505661 is a deficient number, since it is larger than the sum of its proper divisors (35363).

2505661 is an equidigital number, since it uses as much as digits as its factorization.

2505661 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 35362.

The product of its (nonzero) digits is 1800, while the sum is 25.

The square root of 2505661 is about 1582.9279832008. The cubic root of 2505661 is about 135.8232457244.

The spelling of 2505661 in words is "two million, five hundred five thousand, six hundred sixty-one".