1215865823 has 4 divisors (see below), whose sum is σ = 1287387360. Its totient is φ = 1144344288.

The previous prime is 1215865801. The next prime is 1215865829. The reversal of 1215865823 is 3285685121.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 3285685121 = 823 ⋅3992327.

It is a cyclic number.

It is not a de Polignac number, because 1215865823 - 2²² = 1211671519 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1215865829) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 35760743 + ... + 35760776.

It is an arithmetic number, because the mean of its divisors is an integer number (321846840).

Almost surely, 2^1215865823 is an apocalyptic number.

1215865823 is a deficient number, since it is larger than the sum of its proper divisors (71521537).

1215865823 is an equidigital number, since it uses as much as digits as its factorization.

1215865823 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 71521536.

The product of its digits is 115200, while the sum is 41.

The square root of 1215865823 is about 34869.2676005677. The cubic root of 1215865823 is about 1067.3213994781.

The spelling of 1215865823 in words is "one billion, two hundred fifteen million, eight hundred sixty-five thousand, eight hundred twenty-three".