521698 has 4 divisors (see below), whose sum is σ = 782550. Its totient is φ = 260848.

The previous prime is 521693. The next prime is 521707. The reversal of 521698 is 896125.

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

It can be written as a sum of positive squares in only one way, i.e., 471969 + 49729 = 687^2 + 223^2 .

It is a Smith number, since the sum of its digits (31) coincides with the sum of the digits of its prime factors. Since it is squarefree, it is also a hoax number.

It is an Ulam number.

It is an alternating number because its digits alternate between odd and even.

It is not an unprimeable number, because it can be changed into a prime (521693) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 130423 + ... + 130426.

2⁵²¹⁶⁹⁸ is an apocalyptic number.

521698 is a deficient number, since it is larger than the sum of its proper divisors (260852).

521698 is a wasteful number, since it uses less digits than its factorization.

521698 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 260851.

The product of its digits is 4320, while the sum is 31.

The square root of 521698 is about 722.2866466992. The cubic root of 521698 is about 80.5019481802.

The spelling of 521698 in words is "five hundred twenty-one thousand, six hundred ninety-eight".