521625666 has 8 divisors (see below), whose sum is σ = 1043251344. Its totient is φ = 173875220.

The previous prime is 521625653. The next prime is 521625673. The reversal of 521625666 is 666526125.

It is a happy number.

It is a sphenic number, since it is the product of 3 distinct primes.

521625666 is an admirable number.

It is an unprimeable number.

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, 43468800 + ... + 43468811.

It is an arithmetic number, because the mean of its divisors is an integer number (130406418).

Almost surely, 2^521625666 is an apocalyptic number.

521625666 is a primitive abundant number, since it is smaller than the sum of its proper divisors, none of which is abundant.

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

521625666 is a wasteful number, since it uses less digits than its factorization.

521625666 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 86937616.

The product of its digits is 129600, while the sum is 39.

The square root of 521625666 is about 22839.1257713600. The cubic root of 521625666 is about 804.9822744705.

The spelling of 521625666 in words is "five hundred twenty-one million, six hundred twenty-five thousand, six hundred sixty-six".