521651 has 4 divisors (see below), whose sum is σ = 561792. Its totient is φ = 481512.

The previous prime is 521641. The next prime is 521657. The reversal of 521651 is 156125.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 521651 - 2¹⁸ = 259507 is a prime.

It is a Duffinian number.

It is an inconsummate number, since it does not exist a number n which divided by its sum of digits gives 521651.

It is not an unprimeable number, because it can be changed into a prime (521657) 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, 20051 + ... + 20076.

It is an arithmetic number, because the mean of its divisors is an integer number (140448).

2⁵²¹⁶⁵¹ is an apocalyptic number.

521651 is a deficient number, since it is larger than the sum of its proper divisors (40141).

521651 is a wasteful number, since it uses less digits than its factorization.

521651 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 40140.

The product of its digits is 300, while the sum is 20.

The square root of 521651 is about 722.2541104071. The cubic root of 521651 is about 80.4995306224.

Adding to 521651 its reverse (156125), we get a palindrome (677776).

The spelling of 521651 in words is "five hundred twenty-one thousand, six hundred fifty-one".