521661166125 has 64 divisors (see below), whose sum is σ = 951023234304. Its totient is φ = 251840640000.

The previous prime is 521661166123. The next prime is 521661166151.

521661166125 is nontrivially palindromic in base 10.

It is not a de Polignac number, because 521661166125 - 2¹ = 521661166123 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (521661166121) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (23) of ones.

It is a polite number, since it can be written in 63 ways as a sum of consecutive naturals, for example, 689745 + ... + 1232505.

It is an arithmetic number, because the mean of its divisors is an integer number (14859738036).

Almost surely, 2^521661166125 is an apocalyptic number.

521661166125 is a gapful number since it is divisible by the number (55) formed by its first and last digit.

It is an amenable number.

521661166125 is a deficient number, since it is larger than the sum of its proper divisors (429362068179).

521661166125 is a wasteful number, since it uses less digits than its factorization.

521661166125 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 543023 (or 543013 counting only the distinct ones).

The product of its digits is 129600, while the sum is 42.

It can be divided in two parts, 521661 and 166125, that added together give a palindrome (687786).

The spelling of 521661166125 in words is "five hundred twenty-one billion, six hundred sixty-one million, one hundred sixty-six thousand, one hundred twenty-five".