66521213 has 8 divisors (see below), whose sum is σ = 72651936. Its totient is φ = 60404400.

The previous prime is 66521207. The next prime is 66521219. The reversal of 66521213 is 31212566.

It is an interprime number because it is at equal distance from previous prime (66521207) and next prime (66521219).

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 66521213 - 2⁶ = 66521149 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (66521219) 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, 8270 + ... + 14192.

It is an arithmetic number, because the mean of its divisors is an integer number (9081492).

Almost surely, 2^66521213 is an apocalyptic number.

It is an amenable number.

66521213 is a deficient number, since it is larger than the sum of its proper divisors (6130723).

66521213 is a wasteful number, since it uses less digits than its factorization.

66521213 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 6955.

The product of its digits is 2160, while the sum is 26.

The square root of 66521213 is about 8156.0537639228. The cubic root of 66521213 is about 405.1850254511.

Adding to 66521213 its reverse (31212566), we get a palindrome (97733779).

The spelling of 66521213 in words is "sixty-six million, five hundred twenty-one thousand, two hundred thirteen".