1221161165 has 8 divisors (see below), whose sum is σ = 1674735360. Its totient is φ = 837367632.

The previous prime is 1221161129. The next prime is 1221161189. The reversal of 1221161165 is 5611611221.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 1221161165 - 2⁶ = 1221161101 is a prime.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 17445125 + ... + 17445194.

It is an arithmetic number, because the mean of its divisors is an integer number (209341920).

Almost surely, 2^1221161165 is an apocalyptic number.

It is an amenable number.

1221161165 is a deficient number, since it is larger than the sum of its proper divisors (453574195).

1221161165 is an equidigital number, since it uses as much as digits as its factorization.

1221161165 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 34890331.

The product of its digits is 720, while the sum is 26.

The square root of 1221161165 is about 34945.1164685425. The cubic root of 1221161165 is about 1068.8686224706.

Adding to 1221161165 its reverse (5611611221), we get a palindrome (6832772386).

The spelling of 1221161165 in words is "one billion, two hundred twenty-one million, one hundred sixty-one thousand, one hundred sixty-five".