1215043665 has 16 divisors (see below), whose sum is σ = 2120803776. Its totient is φ = 589112000.

The previous prime is 1215043663. The next prime is 1215043691. The reversal of 1215043665 is 5663405121.

It is not a de Polignac number, because 1215043665 - 2¹ = 1215043663 is a prime.

It is a super-2 number, since 2×1215043665² = 2952662215713264450, which contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (33).

It is not an unprimeable number, because it can be changed into a prime (1215043663) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 3681786 + ... + 3682115.

It is an arithmetic number, because the mean of its divisors is an integer number (132550236).

Almost surely, 2^1215043665 is an apocalyptic number.

1215043665 is a gapful number since it is divisible by the number (15) formed by its first and last digit.

It is an amenable number.

1215043665 is a deficient number, since it is larger than the sum of its proper divisors (905760111).

1215043665 is a wasteful number, since it uses less digits than its factorization.

1215043665 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 7363920.

The product of its (nonzero) digits is 21600, while the sum is 33.

The square root of 1215043665 is about 34857.4764577128. The cubic root of 1215043665 is about 1067.0807740537.

Adding to 1215043665 its reverse (5663405121), we get a palindrome (6878448786).

The spelling of 1215043665 in words is "one billion, two hundred fifteen million, forty-three thousand, six hundred sixty-five".