521216520 has 64 divisors (see below), whose sum is σ = 1705803840. Its totient is φ = 126355200.

The previous prime is 521216473. The next prime is 521216537. The reversal of 521216520 is 25612125.

It is a happy number.

It is a Harshad number since it is a multiple of its sum of digits (24).

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 196111 + ... + 198750.

It is an arithmetic number, because the mean of its divisors is an integer number (26653185).

Almost surely, 2^521216520 is an apocalyptic number.

It is an amenable number.

521216520 is an abundant number, since it is smaller than the sum of its proper divisors (1184587320).

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

521216520 is a wasteful number, since it uses less digits than its factorization.

521216520 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 394886 (or 394882 counting only the distinct ones).

The product of its (nonzero) digits is 1200, while the sum is 24.

The square root of 521216520 is about 22830.1668850668. The cubic root of 521216520 is about 804.7717522202.

Adding to 521216520 its reverse (25612125), we get a palindrome (546828645).

The spelling of 521216520 in words is "five hundred twenty-one million, two hundred sixteen thousand, five hundred twenty".