1965820221 has 24 divisors (see below), whose sum is σ = 2901177656. Its totient is φ = 1282314240.

The previous prime is 1965820217. The next prime is 1965820243. The reversal of 1965820221 is 1220285691.

It can be written as a sum of positive squares in 4 ways, for example, as 179828100 + 1785992121 = 13410^2 + 42261^2 .

It is not a de Polignac number, because 1965820221 - 2² = 1965820217 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1965820291) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 96681 + ... + 115233.

Almost surely, 2^1965820221 is an apocalyptic number.

It is an amenable number.

1965820221 is a deficient number, since it is larger than the sum of its proper divisors (935357435).

1965820221 is a wasteful number, since it uses less digits than its factorization.

1965820221 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 18813 (or 18810 counting only the distinct ones).

The product of its (nonzero) digits is 17280, while the sum is 36.

The square root of 1965820221 is about 44337.5712122349. The cubic root of 1965820221 is about 1252.7024669407.

The spelling of 1965820221 in words is "one billion, nine hundred sixty-five million, eight hundred twenty thousand, two hundred twenty-one".