521665716 has 96 divisors (see below), whose sum is σ = 1443657600. Its totient is φ = 144529920.

The previous prime is 521665693. The next prime is 521665751. The reversal of 521665716 is 617566125.

It is a Harshad number since it is a multiple of its sum of digits (39).

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 185650 + ... + 188438.

It is an arithmetic number, because the mean of its divisors is an integer number (15038100).

Almost surely, 2^521665716 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 521665716, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (721828800).

521665716 is an abundant number, since it is smaller than the sum of its proper divisors (921991884).

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

521665716 is a wasteful number, since it uses less digits than its factorization.

521665716 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2929 (or 2927 counting only the distinct ones).

The product of its digits is 75600, while the sum is 39.

The square root of 521665716 is about 22840.0025394044. The cubic root of 521665716 is about 805.0028759076.

The spelling of 521665716 in words is "five hundred twenty-one million, six hundred sixty-five thousand, seven hundred sixteen".