1965867221 has 4 divisors (see below), whose sum is σ = 2013815244. Its totient is φ = 1917919200.

The previous prime is 1965867209. The next prime is 1965867229. The reversal of 1965867221 is 1227685691.

It is a happy number.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 1227685691 = 223 ⋅5505317.

It can be written as a sum of positive squares in 2 ways, for example, as 126315121 + 1839552100 = 11239^2 + 42890^2 .

It is a cyclic number.

It is not a de Polignac number, because 1965867221 - 2⁶ = 1965867157 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 (1965867229) 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, 23973950 + ... + 23974031.

It is an arithmetic number, because the mean of its divisors is an integer number (503453811).

Almost surely, 2^1965867221 is an apocalyptic number.

It is an amenable number.

1965867221 is a deficient number, since it is larger than the sum of its proper divisors (47948023).

1965867221 is an equidigital number, since it uses as much as digits as its factorization.

1965867221 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 47948022.

The product of its digits is 362880, while the sum is 47.

The square root of 1965867221 is about 44338.1012335892. The cubic root of 1965867221 is about 1252.7124503132.

The spelling of 1965867221 in words is "one billion, nine hundred sixty-five million, eight hundred sixty-seven thousand, two hundred twenty-one".