1215139665 has 8 divisors (see below), whose sum is σ = 1944223488. Its totient is φ = 648074480.

The previous prime is 1215139649. The next prime is 1215139669. The reversal of 1215139665 is 5669315121.

It is a happy number.

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

It is not a de Polignac number, because 1215139665 - 2⁴ = 1215139649 is a prime.

It is not an unprimeable number, because it can be changed into a prime (1215139669) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 40504641 + ... + 40504670.

It is an arithmetic number, because the mean of its divisors is an integer number (243027936).

Almost surely, 2^1215139665 is an apocalyptic number.

1215139665 is a gapful number since it is divisible by the number (15) formed by its first and last digit.

It is an amenable number.

1215139665 is a deficient number, since it is larger than the sum of its proper divisors (729083823).

1215139665 is an equidigital number, since it uses as much as digits as its factorization.

1215139665 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 81009319.

The product of its digits is 48600, while the sum is 39.

The square root of 1215139665 is about 34858.8534665155. The cubic root of 1215139665 is about 1067.1088764886.

The spelling of 1215139665 in words is "one billion, two hundred fifteen million, one hundred thirty-nine thousand, six hundred sixty-five".