521669991 has 8 divisors (see below), whose sum is σ = 698546160. Its totient is φ = 346286912.

The previous prime is 521669989. The next prime is 521669999. The reversal of 521669991 is 199966125.

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

It is a cyclic number.

It is not a de Polignac number, because 521669991 - 2¹ = 521669989 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 521669991.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (521669999) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 372456 + ... + 373853.

It is an arithmetic number, because the mean of its divisors is an integer number (87318270).

Almost surely, 2^521669991 is an apocalyptic number.

521669991 is a deficient number, since it is larger than the sum of its proper divisors (176876169).

521669991 is a wasteful number, since it uses less digits than its factorization.

521669991 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 746545.

The product of its digits is 262440, while the sum is 48.

The square root of 521669991 is about 22840.0961250166. The cubic root of 521669991 is about 805.0050748751.

The spelling of 521669991 in words is "five hundred twenty-one million, six hundred sixty-nine thousand, nine hundred ninety-one".