1215665664 has 160 divisors (see below), whose sum is σ = 3354294240. Its totient is φ = 391053312.

The previous prime is 1215665663. The next prime is 1215665683. The reversal of 1215665664 is 4665665121.

Its product of digits (259200) is a multiple of the sum of its prime factors (320).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1215665663) 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, 8873404 + ... + 8873540.

It is an arithmetic number, because the mean of its divisors is an integer number (20964339).

Almost surely, 2^1215665664 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 1215665664, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1677147120).

1215665664 is an abundant number, since it is smaller than the sum of its proper divisors (2138628576).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

1215665664 is a wasteful number, since it uses less digits than its factorization.

1215665664 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 320 (or 304 counting only the distinct ones).

The product of its digits is 259200, while the sum is 42.

The square root of 1215665664 is about 34866.3973475896. The cubic root of 1215665664 is about 1067.2628278539.

The spelling of 1215665664 in words is "one billion, two hundred fifteen million, six hundred sixty-five thousand, six hundred sixty-four".