66851521 has 4 divisors (see below), whose sum is σ = 72928944. Its totient is φ = 60774100.

The previous prime is 66851513. The next prime is 66851539. The reversal of 66851521 is 12515866.

It is a happy number.

66851521 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 66851521 - 2³ = 66851513 is a prime.

It is not an unprimeable number, because it can be changed into a prime (66851581) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 3038695 + ... + 3038716.

It is an arithmetic number, because the mean of its divisors is an integer number (18232236).

Almost surely, 2^66851521 is an apocalyptic number.

It is an amenable number.

66851521 is a deficient number, since it is larger than the sum of its proper divisors (6077423).

66851521 is a wasteful number, since it uses less digits than its factorization.

66851521 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 6077422.

The product of its digits is 14400, while the sum is 34.

The square root of 66851521 is about 8176.2779429273. The cubic root of 66851521 is about 405.8545609764.

The spelling of 66851521 in words is "sixty-six million, eight hundred fifty-one thousand, five hundred twenty-one".