66523813 has 4 divisors (see below), whose sum is σ = 66814540. Its totient is φ = 66233088.

The previous prime is 66523801. The next prime is 66523823. The reversal of 66523813 is 31832566.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 51523684 + 15000129 = 7178^2 + 3873^2 .

It is a cyclic number.

It is not a de Polignac number, because 66523813 - 2⁵ = 66523781 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 (66523823) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 145020 + ... + 145477.

It is an arithmetic number, because the mean of its divisors is an integer number (16703635).

Almost surely, 2^66523813 is an apocalyptic number.

It is an amenable number.

66523813 is a deficient number, since it is larger than the sum of its proper divisors (290727).

66523813 is a wasteful number, since it uses less digits than its factorization.

66523813 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 290726.

The product of its digits is 25920, while the sum is 34.

The square root of 66523813 is about 8156.2131531735. The cubic root of 66523813 is about 405.1903043052.

The spelling of 66523813 in words is "sixty-six million, five hundred twenty-three thousand, eight hundred thirteen".