668572521 has 8 divisors (see below), whose sum is σ = 893914560. Its totient is φ = 444472752.

The previous prime is 668572507. The next prime is 668572529. The reversal of 668572521 is 125275866.

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

It is not a de Polignac number, because 668572521 - 2²⁵ = 635018089 is a prime.

It is not an unprimeable number, because it can be changed into a prime (668572529) 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, 309310 + ... + 311463.

It is an arithmetic number, because the mean of its divisors is an integer number (111739320).

Almost surely, 2^668572521 is an apocalyptic number.

It is an amenable number.

668572521 is a deficient number, since it is larger than the sum of its proper divisors (225342039).

668572521 is a wasteful number, since it uses less digits than its factorization.

668572521 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 621135.

The product of its digits is 201600, while the sum is 42.

The square root of 668572521 is about 25856.7693457632. The cubic root of 668572521 is about 874.4121312785.

It can be divided in two parts, 66857 and 2521, that added together give a triangular number (69378 = T₃₇₂).

The spelling of 668572521 in words is "six hundred sixty-eight million, five hundred seventy-two thousand, five hundred twenty-one".