521504955409 has 3 divisors (see below), whose sum is σ = 521505677563. Its totient is φ = 521504233256.

The previous prime is 521504955397. The next prime is 521504955463. The reversal of 521504955409 is 904559405125.

The square root of 521504955409 is 722153.

It is a perfect power (a square), and thus also a powerful number.

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 only one way, i.e., 438634667025 + 82870288384 = 662295^2 + 287872^2 .

It is not a de Polignac number, because 521504955409 - 2²⁷ = 521370737681 is a prime.

It is a super-2 number, since 2×521504955409² (a number of 24 digits) contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (521504955509) by changing a digit.

It is a polite number, since it can be written in 2 ways as a sum of consecutive naturals, for example, 361077 + ... + 1083229.

Almost surely, 2^521504955409 is an apocalyptic number.

521504955409 is the 722153-rd square number.

521504955409 is the 361077-th centered octagonal number.

It is an amenable number.

521504955409 is a deficient number, since it is larger than the sum of its proper divisors (722154).

521504955409 is an frugal number, since it uses more digits than its factorization.

521504955409 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1444306 (or 722153 counting only the distinct ones).

The product of its (nonzero) digits is 1620000, while the sum is 49.

Multiplying 521504955409 by its sum of digits (49), we get a square (25553742815041 = 5055071²).

The spelling of 521504955409 in words is "five hundred twenty-one billion, five hundred four million, nine hundred fifty-five thousand, four hundred nine".