2051561 has 4 divisors (see below), whose sum is σ = 2054532. Its totient is φ = 2048592.

The previous prime is 2051537. The next prime is 2051587. The reversal of 2051561 is 1651502.

It is a semiprime because it is the product of two primes, and also a brilliant number, because the two primes have the same length.

It can be written as a sum of positive squares in 2 ways, for example, as 1755625 + 295936 = 1325^2 + 544^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-2051561 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (2051461) 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, 155 + ... + 2031.

It is an arithmetic number, because the mean of its divisors is an integer number (513633).

2^2051561 is an apocalyptic number.

It is an amenable number.

2051561 is a deficient number, since it is larger than the sum of its proper divisors (2971).

2051561 is a wasteful number, since it uses less digits than its factorization.

2051561 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2970.

The product of its (nonzero) digits is 300, while the sum is 20.

The square root of 2051561 is about 1432.3271274398. The cubic root of 2051561 is about 127.0656448611.

The spelling of 2051561 in words is "two million, fifty-one thousand, five hundred sixty-one".