521406681 has 4 divisors (see below), whose sum is σ = 695208912. Its totient is φ = 347604452.

The previous prime is 521406679. The next prime is 521406709. The reversal of 521406681 is 186604125.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 521406681 - 2¹ = 521406679 is a prime.

It is a super-2 number, since 2×521406681² = 543729853982871522, which contains 22 as substring.

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (521406181) 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 in 3 ways as a sum of consecutive naturals, for example, 86901111 + ... + 86901116.

It is an arithmetic number, because the mean of its divisors is an integer number (173802228).

Almost surely, 2^521406681 is an apocalyptic number.

It is an amenable number.

521406681 is a deficient number, since it is larger than the sum of its proper divisors (173802231).

521406681 is a wasteful number, since it uses less digits than its factorization.

521406681 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 173802230.

The product of its (nonzero) digits is 11520, while the sum is 33.

The square root of 521406681 is about 22834.3311923078. The cubic root of 521406681 is about 804.8696114833.

The spelling of 521406681 in words is "five hundred twenty-one million, four hundred six thousand, six hundred eighty-one".