521816 has 16 divisors (see below), whose sum is σ = 1030200. Its totient is φ = 247104.

The previous prime is 521813. The next prime is 521819. The reversal of 521816 is 618125.

It is an interprime number because it is at equal distance from previous prime (521813) and next prime (521819).

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

It is a junction number, because it is equal to n+sod(n) for n = 521791 and 521800.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (521813) 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, 1565 + ... + 1868.

2⁵²¹⁸¹⁶ is an apocalyptic number.

It is an amenable number.

521816 is a deficient number, since it is larger than the sum of its proper divisors (508384).

521816 is a wasteful number, since it uses less digits than its factorization.

521816 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3458 (or 3454 counting only the distinct ones).

The product of its digits is 480, while the sum is 23.

The square root of 521816 is about 722.3683271019. The cubic root of 521816 is about 80.5080171535.

The spelling of 521816 in words is "five hundred twenty-one thousand, eight hundred sixteen".