66313521 has 12 divisors (see below), whose sum is σ = 96062148. Its totient is φ = 44081664.

The previous prime is 66313501. The next prime is 66313537. The reversal of 66313521 is 12531366.

66313521 is a `hidden beast` number, since 6 + 631 + 3 + 5 + 21 = 666.

It can be written as a sum of positive squares in 2 ways, for example, as 24206400 + 42107121 = 4920^2 + 6489^2 .

It is not a de Polignac number, because 66313521 - 2¹³ = 66305329 is a prime.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (66313501) 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 11 ways as a sum of consecutive naturals, for example, 7260 + ... + 13613.

It is an arithmetic number, because the mean of its divisors is an integer number (8005179).

Almost surely, 2^66313521 is an apocalyptic number.

It is an amenable number.

66313521 is a deficient number, since it is larger than the sum of its proper divisors (29748627).

66313521 is a wasteful number, since it uses less digits than its factorization.

66313521 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 21232 (or 21229 counting only the distinct ones).

The product of its digits is 3240, while the sum is 27.

The square root of 66313521 is about 8143.3114271775. The cubic root of 66313521 is about 404.7628973406.

Adding to 66313521 its reverse (12531366), we get a palindrome (78844887).

The spelling of 66313521 in words is "sixty-six million, three hundred thirteen thousand, five hundred twenty-one".