513521721 has 16 divisors (see below), whose sum is σ = 800814400. Its totient is φ = 324329184.

The previous prime is 513521711. The next prime is 513521777. The reversal of 513521721 is 127125315.

It is not a de Polignac number, because 513521721 - 2¹⁸ = 513259577 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (27).

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (513521711) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 499996 + ... + 501021.

It is an arithmetic number, because the mean of its divisors is an integer number (50050900).

Almost surely, 2^513521721 is an apocalyptic number.

It is an amenable number.

513521721 is a deficient number, since it is larger than the sum of its proper divisors (287292679).

513521721 is a wasteful number, since it uses less digits than its factorization.

513521721 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1001045 (or 1001039 counting only the distinct ones).

The product of its digits is 2100, while the sum is 27.

The square root of 513521721 is about 22661.0176514648. The cubic root of 513521721 is about 800.7917791196.

The spelling of 513521721 in words is "five hundred thirteen million, five hundred twenty-one thousand, seven hundred twenty-one".