66410021 has 4 divisors (see below), whose sum is σ = 66513312. Its totient is φ = 66306732.

The previous prime is 66409991. The next prime is 66410023. The reversal of 66410021 is 12001466.

It is a happy number.

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: 12001466 = 2 ⋅6000733.

It is a cyclic number.

It is not a de Polignac number, because 66410021 - 2⁶ = 66409957 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 66409975 and 66410002.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (66410023) 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, 50675 + ... + 51968.

It is an arithmetic number, because the mean of its divisors is an integer number (16628328).

Almost surely, 2^66410021 is an apocalyptic number.

It is an amenable number.

66410021 is a deficient number, since it is larger than the sum of its proper divisors (103291).

66410021 is a wasteful number, since it uses less digits than its factorization.

66410021 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 103290.

The product of its (nonzero) digits is 288, while the sum is 20.

The square root of 66410021 is about 8149.2343812164. The cubic root of 66410021 is about 404.9591403172.

Adding to 66410021 its reverse (12001466), we get a palindrome (78411487).

The spelling of 66410021 in words is "sixty-six million, four hundred ten thousand, twenty-one".