1281166121 has 4 divisors (see below), whose sum is σ = 1356528852. Its totient is φ = 1205803392.

The previous prime is 1281166097. The next prime is 1281166157. The reversal of 1281166121 is 1216611821.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 980629225 + 300536896 = 31315^2 + 17336^2 .

It is a cyclic number.

It is not a de Polignac number, because 1281166121 - 2¹⁸ = 1280903977 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (1281166021) 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, 37681340 + ... + 37681373.

It is an arithmetic number, because the mean of its divisors is an integer number (339132213).

Almost surely, 2^1281166121 is an apocalyptic number.

It is an amenable number.

1281166121 is a deficient number, since it is larger than the sum of its proper divisors (75362731).

1281166121 is an equidigital number, since it uses as much as digits as its factorization.

1281166121 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 75362730.

The product of its digits is 1152, while the sum is 29.

The square root of 1281166121 is about 35793.3809663183. The cubic root of 1281166121 is about 1086.0966694119.

Adding to 1281166121 its reverse (1216611821), we get a palindrome (2497777942).

The spelling of 1281166121 in words is "one billion, two hundred eighty-one million, one hundred sixty-six thousand, one hundred twenty-one".