18821961 has 12 divisors (see below), whose sum is σ = 27225588. Its totient is φ = 12530304.

The previous prime is 18821947. The next prime is 18821963. The reversal of 18821961 is 16912881.

It can be written as a sum of positive squares in 2 ways, for example, as 4076361 + 14745600 = 2019^2 + 3840^2 .

It is not a de Polignac number, because 18821961 - 2⁶ = 18821897 is a prime.

It is a Smith number, since the sum of its digits (36) coincides with the sum of the digits of its prime factors.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (18821963) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 9861 + ... + 11613.

It is an arithmetic number, because the mean of its divisors is an integer number (2268799).

Almost surely, 2^18821961 is an apocalyptic number.

It is an amenable number.

18821961 is a deficient number, since it is larger than the sum of its proper divisors (8403627).

18821961 is a wasteful number, since it uses less digits than its factorization.

18821961 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2952 (or 2949 counting only the distinct ones).

The product of its digits is 6912, while the sum is 36.

The square root of 18821961 is about 4338.4284020829. The cubic root of 18821961 is about 266.0040749748.

The spelling of 18821961 in words is "eighteen million, eight hundred twenty-one thousand, nine hundred sixty-one".