1212405665 has 4 divisors (see below), whose sum is σ = 1454886804. Its totient is φ = 969924528.

The previous prime is 1212405661. The next prime is 1212405673. The reversal of 1212405665 is 5665042121.

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 907274641 + 305131024 = 30121^2 + 17468^2 .

It is a cyclic number.

It is not a de Polignac number, because 1212405665 - 2² = 1212405661 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (1212405661) 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, 121240562 + ... + 121240571.

It is an arithmetic number, because the mean of its divisors is an integer number (363721701).

Almost surely, 2^1212405665 is an apocalyptic number.

It is an amenable number.

1212405665 is a deficient number, since it is larger than the sum of its proper divisors (242481139).

1212405665 is an equidigital number, since it uses as much as digits as its factorization.

1212405665 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 242481138.

The product of its (nonzero) digits is 14400, while the sum is 32.

The square root of 1212405665 is about 34819.6160949543. The cubic root of 1212405665 is about 1066.3079626658.

Adding to 1212405665 its reverse (5665042121), we get a palindrome (6877447786).

The spelling of 1212405665 in words is "one billion, two hundred twelve million, four hundred five thousand, six hundred sixty-five".