1561601 has 2 divisors, whose sum is σ = 1561602. Its totient is φ = 1561600.

The previous prime is 1561597. The next prime is 1561607. The reversal of 1561601 is 1061651.

It is a happy number.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 1560001 + 1600 = 1249^2 + 40^2 .

It is an emirp because it is prime and its reverse (1061651) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 1561601 - 2² = 1561597 is a prime.

It is a Sophie Germain prime.

It is a Curzon number.

It is not a weakly prime, because it can be changed into another prime (1561607) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 780800 + 780801.

It is an arithmetic number, because the mean of its divisors is an integer number (780801).

2^1561601 is an apocalyptic number.

It is an amenable number.

1561601 is a deficient number, since it is larger than the sum of its proper divisors (1).

1561601 is an equidigital number, since it uses as much as digits as its factorization.

1561601 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 180, while the sum is 20.

The square root of 1561601 is about 1249.6403482603. The cubic root of 1561601 is about 116.0174616995.

It can be divided in two parts, 15 and 61601, that added together give a palindrome (61616).

The spelling of 1561601 in words is "one million, five hundred sixty-one thousand, six hundred one".