523640021 has 8 divisors (see below), whose sum is σ = 539787264. Its totient is φ = 507597840.

The previous prime is 523640009. The next prime is 523640027. The reversal of 523640021 is 120046325.

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 523640021 - 2⁶ = 523639957 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (523640027) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 16085 + ... + 36138.

It is an arithmetic number, because the mean of its divisors is an integer number (67473408).

Almost surely, 2^523640021 is an apocalyptic number.

It is an amenable number.

523640021 is a deficient number, since it is larger than the sum of its proper divisors (16147243).

523640021 is a wasteful number, since it uses less digits than its factorization.

523640021 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 52531.

The product of its (nonzero) digits is 1440, while the sum is 23.

The square root of 523640021 is about 22883.1820558243. The cubic root of 523640021 is about 806.0171400033.

Adding to 523640021 its reverse (120046325), we get a palindrome (643686346).

The spelling of 523640021 in words is "five hundred twenty-three million, six hundred forty thousand, twenty-one".