521643 has 8 divisors (see below), whose sum is σ = 712656. Its totient is φ = 339200.

The previous prime is 521641. The next prime is 521657. The reversal of 521643 is 346125.

It is a happy number.

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 521643 - 2¹ = 521641 is a prime.

It is a super-2 number, since 2×521643² = 544222838898, which contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (521641) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 1998 + ... + 2243.

It is an arithmetic number, because the mean of its divisors is an integer number (89082).

2⁵²¹⁶⁴³ is an apocalyptic number.

521643 is a deficient number, since it is larger than the sum of its proper divisors (191013).

521643 is a wasteful number, since it uses less digits than its factorization.

521643 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4285.

The product of its digits is 720, while the sum is 21.

The square root of 521643 is about 722.2485721689. The cubic root of 521643 is about 80.4991191087.

Adding to 521643 its reverse (346125), we get a palindrome (867768).

The spelling of 521643 in words is "five hundred twenty-one thousand, six hundred forty-three".