665689920 has 448 divisors, whose sum is σ = 2598359040. Its totient is φ = 141115392.

The previous prime is 665689879. The next prime is 665689933. The reversal of 665689920 is 29986566.

It is a tau number, because it is divible by the number of its divisors (448).

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 63 ways as a sum of consecutive naturals, for example, 9119004 + ... + 9119076.

Almost surely, 2^665689920 is an apocalyptic number.

665689920 is a gapful number since it is divisible by the number (60) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 665689920, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1299179520).

665689920 is an abundant number, since it is smaller than the sum of its proper divisors (1932669120).

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

665689920 is a wasteful number, since it uses less digits than its factorization.

665689920 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 182 (or 172 counting only the distinct ones).

The product of its (nonzero) digits is 1399680, while the sum is 51.

The square root of 665689920 is about 25800.9674237227. The cubic root of 665689920 is about 873.1536228067.

The spelling of 665689920 in words is "six hundred sixty-five million, six hundred eighty-nine thousand, nine hundred twenty".