1918561 has 4 divisors (see below), whose sum is σ = 1970452. Its totient is φ = 1866672.

The previous prime is 1918549. The next prime is 1918571. The reversal of 1918561 is 1658191.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 1658191 = 29 ⋅57179.

It can be written as a sum of positive squares in 2 ways, for example, as 1806336 + 112225 = 1344^2 + 335^2 .

It is a cyclic number.

It is not a de Polignac number, because 1918561 - 2⁵ = 1918529 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (1918571) 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, 25890 + ... + 25963.

It is an arithmetic number, because the mean of its divisors is an integer number (492613).

2^1918561 is an apocalyptic number.

It is an amenable number.

1918561 is a deficient number, since it is larger than the sum of its proper divisors (51891).

1918561 is an equidigital number, since it uses as much as digits as its factorization.

1918561 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 51890.

The product of its digits is 2160, while the sum is 31.

The square root of 1918561 is about 1385.1212943277. The cubic root of 1918561 is about 124.2582417306.

The spelling of 1918561 in words is "one million, nine hundred eighteen thousand, five hundred sixty-one".