66207121 has 4 divisors (see below), whose sum is σ = 66227200. Its totient is φ = 66187044.

The previous prime is 66207109. The next prime is 66207137. The reversal of 66207121 is 12170266.

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 66207121 - 2¹⁹ = 65682833 is a prime.

It is a super-2 number, since 2×66207121² = 8766765742217282, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (66207181) 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, 3801 + ... + 12118.

It is an arithmetic number, because the mean of its divisors is an integer number (16556800).

Almost surely, 2^66207121 is an apocalyptic number.

It is an amenable number.

66207121 is a deficient number, since it is larger than the sum of its proper divisors (20079).

66207121 is a wasteful number, since it uses less digits than its factorization.

66207121 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 20078.

The product of its (nonzero) digits is 1008, while the sum is 25.

The square root of 66207121 is about 8136.7758356735. The cubic root of 66207121 is about 404.5463008571.

Adding to 66207121 its reverse (12170266), we get a palindrome (78377387).

The spelling of 66207121 in words is "sixty-six million, two hundred seven thousand, one hundred twenty-one".