2621561 has 4 divisors (see below), whose sum is σ = 2692452. Its totient is φ = 2550672.

The previous prime is 2621551. The next prime is 2621569. The reversal of 2621561 is 1651262.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 2325625 + 295936 = 1525^2 + 544^2 .

It is a cyclic number.

It is not a de Polignac number, because 2621561 - 2¹⁴ = 2605177 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (2621569) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (7) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 35390 + ... + 35463.

It is an arithmetic number, because the mean of its divisors is an integer number (673113).

2^2621561 is an apocalyptic number.

It is an amenable number.

2621561 is a deficient number, since it is larger than the sum of its proper divisors (70891).

2621561 is an equidigital number, since it uses as much as digits as its factorization.

2621561 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 70890.

The product of its digits is 720, while the sum is 23.

The square root of 2621561 is about 1619.1235283325. The cubic root of 2621561 is about 137.8859416024.

Subtracting from 2621561 its reverse (1651262), we obtain a cube (970299 = 99³).

The spelling of 2621561 in words is "two million, six hundred twenty-one thousand, five hundred sixty-one".