665945520 has 160 divisors (see below), whose sum is σ = 2116364544. Its totient is φ = 173184000.

The previous prime is 665945507. The next prime is 665945521. The reversal of 665945520 is 25549566.

It is not an unprimeable number, because it can be changed into a prime (665945521) 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, 2011755 + ... + 2012085.

Almost surely, 2^665945520 is an apocalyptic number.

665945520 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 665945520, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1058182272).

665945520 is an abundant number, since it is smaller than the sum of its proper divisors (1450419024).

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

665945520 is a wasteful number, since it uses less digits than its factorization.

665945520 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 531 (or 525 counting only the distinct ones).

The product of its (nonzero) digits is 324000, while the sum is 42.

The square root of 665945520 is about 25805.9202509812. The cubic root of 665945520 is about 873.2653612710.

The spelling of 665945520 in words is "six hundred sixty-five million, nine hundred forty-five thousand, five hundred twenty".