1561001 has 4 divisors (see below), whose sum is σ = 1681092. Its totient is φ = 1440912.

The previous prime is 1560997. The next prime is 1561003. The reversal of 1561001 is 1001651.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 1001651 = 7 ⋅143093.

It can be written as a sum of positive squares in 2 ways, for example, as 1000000 + 561001 = 1000^2 + 749^2 .

It is a cyclic number.

It is not a de Polignac number, because 1561001 - 2² = 1560997 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (1561003) 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, 60026 + ... + 60051.

It is an arithmetic number, because the mean of its divisors is an integer number (420273).

2^1561001 is an apocalyptic number.

It is an amenable number.

1561001 is a deficient number, since it is larger than the sum of its proper divisors (120091).

1561001 is a wasteful number, since it uses less digits than its factorization.

1561001 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 120090.

The product of its (nonzero) digits is 30, while the sum is 14.

The square root of 1561001 is about 1249.4002561229. The cubic root of 1561001 is about 116.0026010118.

Adding to 1561001 its reverse (1001651), we get a palindrome (2562652).

It can be divided in two parts, 15 and 61001, that added together give a palindrome (61016).

The spelling of 1561001 in words is "one million, five hundred sixty-one thousand, one".