2128561 has 2 divisors, whose sum is σ = 2128562. Its totient is φ = 2128560.

The previous prime is 2128559. The next prime is 2128591. The reversal of 2128561 is 1658212.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 1575025 + 553536 = 1255^2 + 744^2 .

It is a cyclic number.

It is not a de Polignac number, because 2128561 - 2¹ = 2128559 is a prime.

Together with 2128559, it forms a pair of twin primes.

It is not a weakly prime, because it can be changed into another prime (2128501) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 1064280 + 1064281.

It is an arithmetic number, because the mean of its divisors is an integer number (1064281).

2^2128561 is an apocalyptic number.

It is an amenable number.

2128561 is a deficient number, since it is larger than the sum of its proper divisors (1).

2128561 is an equidigital number, since it uses as much as digits as its factorization.

2128561 is an evil number, because the sum of its binary digits is even.

The product of its digits is 960, while the sum is 25.

The square root of 2128561 is about 1458.9588753628. The cubic root of 2128561 is about 128.6358538379.

It can be divided in two parts, 21 and 28561, that added together give a palindrome (28582).

The spelling of 2128561 in words is "two million, one hundred twenty-eight thousand, five hundred sixty-one".