1215665525 has 12 divisors (see below), whose sum is σ = 1548167652. Its totient is φ = 946247040.

The previous prime is 1215665491. The next prime is 1215665557. The reversal of 1215665525 is 5255665121.

It can be written as a sum of positive squares in 6 ways, for example, as 32924644 + 1182740881 = 5738^2 + 34391^2 .

It is not a de Polignac number, because 1215665525 - 2¹⁰ = 1215664501 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 656192 + ... + 658041.

It is an arithmetic number, because the mean of its divisors is an integer number (129013971).

Almost surely, 2^1215665525 is an apocalyptic number.

It is an amenable number.

1215665525 is a deficient number, since it is larger than the sum of its proper divisors (332502127).

1215665525 is a wasteful number, since it uses less digits than its factorization.

1215665525 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1314280 (or 1314275 counting only the distinct ones).

The product of its digits is 90000, while the sum is 38.

The square root of 1215665525 is about 34866.3953542663. The cubic root of 1215665525 is about 1067.2627871767.

The spelling of 1215665525 in words is "one billion, two hundred fifteen million, six hundred sixty-five thousand, five hundred twenty-five".