1212101665 has 4 divisors (see below), whose sum is σ = 1454522004. Its totient is φ = 969681328.

The previous prime is 1212101641. The next prime is 1212101677. The reversal of 1212101665 is 5661012121.

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: 5661012121 = 17 ⋅333000713.

It can be written as a sum of positive squares in 2 ways, for example, as 543775761 + 668325904 = 23319^2 + 25852^2 .

It is a cyclic number.

It is not a de Polignac number, because 1212101665 - 2⁹ = 1212101153 is a prime.

It is a Duffinian number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 121210162 + ... + 121210171.

It is an arithmetic number, because the mean of its divisors is an integer number (363630501).

Almost surely, 2^1212101665 is an apocalyptic number.

It is an amenable number.

1212101665 is a deficient number, since it is larger than the sum of its proper divisors (242420339).

1212101665 is an equidigital number, since it uses as much as digits as its factorization.

1212101665 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 242420338.

The product of its (nonzero) digits is 720, while the sum is 25.

The square root of 1212101665 is about 34815.2504658519. The cubic root of 1212101665 is about 1066.2188327849.

Adding to 1212101665 its reverse (5661012121), we get a palindrome (6873113786).

The spelling of 1212101665 in words is "one billion, two hundred twelve million, one hundred one thousand, six hundred sixty-five".