66523421 has 4 divisors (see below), whose sum is σ = 67324992. Its totient is φ = 65721852.

The previous prime is 66523411. The next prime is 66523423. The reversal of 66523421 is 12432566.

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, and also an emirpimes, since its reverse is a distinct semiprime: 12432566 = 2 ⋅6216283.

It is a cyclic number.

It is not a de Polignac number, because 66523421 - 2²² = 62329117 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 (66523423) 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, 400661 + ... + 400826.

It is an arithmetic number, because the mean of its divisors is an integer number (16831248).

Almost surely, 2^66523421 is an apocalyptic number.

It is an amenable number.

66523421 is a deficient number, since it is larger than the sum of its proper divisors (801571).

66523421 is an equidigital number, since it uses as much as digits as its factorization.

66523421 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 801570.

The product of its digits is 8640, while the sum is 29.

The square root of 66523421 is about 8156.1891223782. The cubic root of 66523421 is about 405.1895084253.

Adding to 66523421 its reverse (12432566), we get a palindrome (78955987).

The spelling of 66523421 in words is "sixty-six million, five hundred twenty-three thousand, four hundred twenty-one".