66664121 has 4 divisors (see below), whose sum is σ = 68465892. Its totient is φ = 64862352.

The previous prime is 66664109. The next prime is 66664133. The reversal of 66664121 is 12146666.

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

It is an interprime number because it is at equal distance from previous prime (66664109) and next prime (66664133).

It can be written as a sum of positive squares in 2 ways, for example, as 60217600 + 6446521 = 7760^2 + 2539^2 .

It is a cyclic number.

It is not a de Polignac number, because 66664121 - 2⁶ = 66664057 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (66664181) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 900830 + ... + 900903.

It is an arithmetic number, because the mean of its divisors is an integer number (17116473).

Almost surely, 2^66664121 is an apocalyptic number.

It is an amenable number.

66664121 is a deficient number, since it is larger than the sum of its proper divisors (1801771).

66664121 is a wasteful number, since it uses less digits than its factorization.

66664121 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1801770.

The product of its digits is 10368, while the sum is 32.

The square root of 66664121 is about 8164.8099181794. The cubic root of 66664121 is about 405.4749718862.

The spelling of 66664121 in words is "sixty-six million, six hundred sixty-four thousand, one hundred twenty-one".