2561749 has 2 divisors, whose sum is σ = 2561750. Its totient is φ = 2561748.

The previous prime is 2561743. The next prime is 2561753. The reversal of 2561749 is 9471652.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 2387025 + 174724 = 1545^2 + 418^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-2561749 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (2561743) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 1280874 + 1280875.

It is an arithmetic number, because the mean of its divisors is an integer number (1280875).

2^2561749 is an apocalyptic number.

It is an amenable number.

2561749 is a deficient number, since it is larger than the sum of its proper divisors (1).

2561749 is an equidigital number, since it uses as much as digits as its factorization.

2561749 is an evil number, because the sum of its binary digits is even.

The product of its digits is 15120, while the sum is 34.

The square root of 2561749 is about 1600.5464691786. The cubic root of 2561749 is about 136.8292222664.

Subtracting 2561749 from its reverse (9471652), we obtain a triangular number (6909903 = T₃₇₁₇).

It can be divided in two parts, 256 and 1749, that multiplied together give a palindrome (447744).

The spelling of 2561749 in words is "two million, five hundred sixty-one thousand, seven hundred forty-nine".