521661520 has 40 divisors (see below), whose sum is σ = 1245650184. Its totient is φ = 203023872.

The previous prime is 521661499. The next prime is 521661527. The reversal of 521661520 is 25166125.

It can be written as a sum of positive squares in 4 ways, for example, as 309900816 + 211760704 = 17604^2 + 14552^2 .

It is a tau number, because it is divible by the number of its divisors (40).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (521661527) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 85159 + ... + 91078.

Almost surely, 2^521661520 is an apocalyptic number.

It is an amenable number.

521661520 is an abundant number, since it is smaller than the sum of its proper divisors (723988664).

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

521661520 is a wasteful number, since it uses less digits than its factorization.

521661520 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 176287 (or 176281 counting only the distinct ones).

The product of its (nonzero) digits is 3600, while the sum is 28.

The square root of 521661520 is about 22839.9106828376. The cubic root of 521661520 is about 805.0007175643. Note that the first 3 decimals are identical.

The spelling of 521661520 in words is "five hundred twenty-one million, six hundred sixty-one thousand, five hundred twenty".