2561690 has 8 divisors (see below), whose sum is σ = 4611060. Its totient is φ = 1024672.

The previous prime is 2561683. The next prime is 2561723. The reversal of 2561690 is 961652.

2561690 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It can be written as a sum of positive squares in 2 ways, for example, as 2217121 + 344569 = 1489^2 + 587^2 .

It is a sphenic number, since it is the product of 3 distinct primes.

It is a super-2 number, since 2×2561690² = 13124511312200, which contains 22 as substring.

It is an alternating number because its digits alternate between even and odd.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 128075 + ... + 128094.

2^2561690 is an apocalyptic number.

2561690 is a deficient number, since it is larger than the sum of its proper divisors (2049370).

2561690 is a wasteful number, since it uses less digits than its factorization.

2561690 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 256176.

The product of its (nonzero) digits is 3240, while the sum is 29.

The square root of 2561690 is about 1600.5280378675. The cubic root of 2561690 is about 136.8281718140.

The spelling of 2561690 in words is "two million, five hundred sixty-one thousand, six hundred ninety".