9666658638 has 384 divisors, whose sum is σ = 28827187200. Its totient is φ = 2333422080.

The previous prime is 9666658583. The next prime is 9666658663. The reversal of 9666658638 is 8368566669.

It is a Harshad number since it is a multiple of its sum of digits (63).

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 191 ways as a sum of consecutive naturals, for example, 108614098 + ... + 108614186.

It is an arithmetic number, because the mean of its divisors is an integer number (75070800).

Almost surely, 2^9666658638 is an apocalyptic number.

It is a practical number, because each smaller number is the sum of distinct divisors of 9666658638, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (14413593600).

9666658638 is an abundant number, since it is smaller than the sum of its proper divisors (19160528562).

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

9666658638 is a wasteful number, since it uses less digits than its factorization.

9666658638 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 205 (or 168 counting only the distinct ones).

The product of its digits is 67184640, while the sum is 63.

The square root of 9666658638 is about 98319.1671954152. The cubic root of 9666658638 is about 2130.2249197121.

The spelling of 9666658638 in words is "nine billion, six hundred sixty-six million, six hundred fifty-eight thousand, six hundred thirty-eight".