1866244221 has 48 divisors (see below), whose sum is σ = 2885454000. Its totient is φ = 1160054784.

The previous prime is 1866244217. The next prime is 1866244229. The reversal of 1866244221 is 1224426681.

1866244221 is a `hidden beast` number, since 1 + 8 + 6 + 624 + 4 + 2 + 21 = 666.

It can be written as a sum of positive squares in 8 ways, for example, as 265364100 + 1600880121 = 16290^2 + 40011^2 .

It is not a de Polignac number, because 1866244221 - 2² = 1866244217 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1866244229) by changing a digit.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 1438245 + ... + 1439541.

It is an arithmetic number, because the mean of its divisors is an integer number (60113625).

Almost surely, 2^1866244221 is an apocalyptic number.

It is an amenable number.

1866244221 is a deficient number, since it is larger than the sum of its proper divisors (1019209779).

1866244221 is a wasteful number, since it uses less digits than its factorization.

1866244221 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1518 (or 1515 counting only the distinct ones).

The product of its digits is 36864, while the sum is 36.

The square root of 1866244221 is about 43200.0488541390. The cubic root of 1866244221 is about 1231.1836098226.

The spelling of 1866244221 in words is "one billion, eight hundred sixty-six million, two hundred forty-four thousand, two hundred twenty-one".