1831561 has 4 divisors (see below), whose sum is σ = 1853712. Its totient is φ = 1809412.

The previous prime is 1831523. The next prime is 1831589. The reversal of 1831561 is 1651381.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4, and also an emirpimes, since its reverse is a distinct semiprime: 1651381 = 127 ⋅13003.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-1831561 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (1831591) 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, 10951 + ... + 11116.

It is an arithmetic number, because the mean of its divisors is an integer number (463428).

2^1831561 is an apocalyptic number.

It is an amenable number.

1831561 is a deficient number, since it is larger than the sum of its proper divisors (22151).

1831561 is an equidigital number, since it uses as much as digits as its factorization.

1831561 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 22150.

The product of its digits is 720, while the sum is 25.

The square root of 1831561 is about 1353.3517650633. The cubic root of 1831561 is about 122.3508889581.

The spelling of 1831561 in words is "one million, eight hundred thirty-one thousand, five hundred sixty-one".