1216661526 has 64 divisors (see below), whose sum is σ = 2803507200. Its totient is φ = 390700800.

The previous prime is 1216661513. The next prime is 1216661527. The reversal of 1216661526 is 6251666121.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1216661527) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 398566 + ... + 401606.

It is an arithmetic number, because the mean of its divisors is an integer number (43804800).

Almost surely, 2^1216661526 is an apocalyptic number.

It is a practical number, because each smaller number is the sum of distinct divisors of 1216661526, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1401753600).

1216661526 is an abundant number, since it is smaller than the sum of its proper divisors (1586845674).

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

1216661526 is a wasteful number, since it uses less digits than its factorization.

1216661526 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3322 (or 3316 counting only the distinct ones).

The product of its digits is 25920, while the sum is 36.

The square root of 1216661526 is about 34880.6755381830. The cubic root of 1216661526 is about 1067.5541789035.

The spelling of 1216661526 in words is "one billion, two hundred sixteen million, six hundred sixty-one thousand, five hundred twenty-six".