511721521 has 4 divisors (see below), whose sum is σ = 511769700. Its totient is φ = 511673344.

The previous prime is 511721489. The next prime is 511721527. The reversal of 511721521 is 125127115.

It is a semiprime because it is the product of two primes, and also a brilliant number, because the two primes have the same length.

It can be written as a sum of positive squares in 2 ways, for example, as 20611600 + 491109921 = 4540^2 + 22161^2 .

It is a cyclic number.

It is not a de Polignac number, because 511721521 - 2⁵ = 511721489 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (511721527) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 376 + ... + 31993.

It is an arithmetic number, because the mean of its divisors is an integer number (127942425).

Almost surely, 2^511721521 is an apocalyptic number.

It is an amenable number.

511721521 is a deficient number, since it is larger than the sum of its proper divisors (48179).

511721521 is a wasteful number, since it uses less digits than its factorization.

511721521 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 48178.

The product of its digits is 700, while the sum is 25.

The square root of 511721521 is about 22621.2625863368. The cubic root of 511721521 is about 799.8549325501.

Adding to 511721521 its reverse (125127115), we get a palindrome (636848636).

The spelling of 511721521 in words is "five hundred eleven million, seven hundred twenty-one thousand, five hundred twenty-one".