521663 has 8 divisors (see below), whose sum is σ = 559968. Its totient is φ = 484704.

The previous prime is 521659. The next prime is 521669. The reversal of 521663 is 366125.

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 521663 - 2² = 521659 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (23).

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (521669) 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, 545 + ... + 1157.

It is an arithmetic number, because the mean of its divisors is an integer number (69996).

2⁵²¹⁶⁶³ is an apocalyptic number.

521663 is a deficient number, since it is larger than the sum of its proper divisors (38305).

521663 is a wasteful number, since it uses less digits than its factorization.

521663 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 673.

The product of its digits is 1080, while the sum is 23.

The square root of 521663 is about 722.2624176849. The cubic root of 521663 is about 80.5001478850.

Adding to 521663 its reverse (366125), we get a palindrome (887788).

The spelling of 521663 in words is "five hundred twenty-one thousand, six hundred sixty-three".