665261520 has 160 divisors (see below), whose sum is σ = 2571264000. Its totient is φ = 138232320.

The previous prime is 665261507. The next prime is 665261563. The reversal of 665261520 is 25162566.

It is a happy number.

665261520 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a Harshad number since it is a multiple of its sum of digits (33).

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 481 + ... + 36479.

It is an arithmetic number, because the mean of its divisors is an integer number (16070400).

Almost surely, 2^665261520 is an apocalyptic number.

665261520 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 665261520, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1285632000).

665261520 is an abundant number, since it is smaller than the sum of its proper divisors (1906002480).

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

665261520 is a wasteful number, since it uses less digits than its factorization.

665261520 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 36033 (or 36027 counting only the distinct ones).

The product of its (nonzero) digits is 21600, while the sum is 33.

The square root of 665261520 is about 25792.6640733368. The cubic root of 665261520 is about 872.9662786842.

The spelling of 665261520 in words is "six hundred sixty-five million, two hundred sixty-one thousand, five hundred twenty".