66606921 has 8 divisors (see below), whose sum is σ = 98676960. Its totient is φ = 44404596.

The previous prime is 66606899. The next prime is 66606923. The reversal of 66606921 is 12960666.

It is a happy number.

It is not a de Polignac number, because 66606921 - 2⁵ = 66606889 is a prime.

It is not an unprimeable number, because it can be changed into a prime (66606923) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 1233435 + ... + 1233488.

It is an arithmetic number, because the mean of its divisors is an integer number (12334620).

Almost surely, 2^66606921 is an apocalyptic number.

It is an amenable number.

66606921 is a deficient number, since it is larger than the sum of its proper divisors (32070039).

66606921 is a wasteful number, since it uses less digits than its factorization.

66606921 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2466932 (or 2466926 counting only the distinct ones).

The product of its (nonzero) digits is 23328, while the sum is 36.

The square root of 66606921 is about 8161.3063292588. The cubic root of 66606921 is about 405.3589684314.

The spelling of 66606921 in words is "sixty-six million, six hundred six thousand, nine hundred twenty-one".