1811961 has 6 divisors (see below), whose sum is σ = 2617290. Its totient is φ = 1207968.

The previous prime is 1811959. The next prime is 1811983. The reversal of 1811961 is 1691181.

It can be written as a sum of positive squares in only one way, i.e., 1806336 + 5625 = 1344^2 + 75^2 .

It is not a de Polignac number, because 1811961 - 2¹ = 1811959 is a prime.

It is an Ulam number.

It is not an unprimeable number, because it can be changed into a prime (1811561) by changing a digit.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 100656 + ... + 100673.

It is an arithmetic number, because the mean of its divisors is an integer number (436215).

2^1811961 is an apocalyptic number.

It is an amenable number.

1811961 is a deficient number, since it is larger than the sum of its proper divisors (805329).

1811961 is a wasteful number, since it uses less digits than its factorization.

1811961 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 201335 (or 201332 counting only the distinct ones).

The product of its digits is 432, while the sum is 27.

The square root of 1811961 is about 1346.0910073245. The cubic root of 1811961 is about 121.9128868404.

It can be divided in two parts, 1811 and 961, that added together give a palindrome (2772).

The spelling of 1811961 in words is "one million, eight hundred eleven thousand, nine hundred sixty-one".