521216521 has 8 divisors (see below), whose sum is σ = 611775680. Its totient is φ = 434682288.

The previous prime is 521216473. The next prime is 521216537. The reversal of 521216521 is 125612125.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 521216521 - 2¹⁵ = 521183753 is a prime.

It is an alternating number because its digits alternate between odd and even.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (521216021) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 1005951 + ... + 1006468.

It is an arithmetic number, because the mean of its divisors is an integer number (76471960).

Almost surely, 2^521216521 is an apocalyptic number.

It is an amenable number.

521216521 is a deficient number, since it is larger than the sum of its proper divisors (90559159).

521216521 is a wasteful number, since it uses less digits than its factorization.

521216521 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2012463.

The product of its digits is 1200, while the sum is 25.

The square root of 521216521 is about 22830.1669069676. The cubic root of 521216521 is about 804.7717527349.

Adding to 521216521 its reverse (125612125), we get a palindrome (646828646).

The spelling of 521216521 in words is "five hundred twenty-one million, two hundred sixteen thousand, five hundred twenty-one".