66600021 has 8 divisors (see below), whose sum is σ = 89182080. Its totient is φ = 44208992.

The previous prime is 66599989. The next prime is 66600029. The reversal of 66600021 is 12000666.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 66600021 - 2⁵ = 66599989 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (66600029) 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, 46941 + ... + 48338.

It is an arithmetic number, because the mean of its divisors is an integer number (11147760).

Almost surely, 2^66600021 is an apocalyptic number.

It is an amenable number.

66600021 is a deficient number, since it is larger than the sum of its proper divisors (22582059).

66600021 is a wasteful number, since it uses less digits than its factorization.

66600021 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 95515.

The product of its (nonzero) digits is 432, while the sum is 21.

The square root of 66600021 is about 8160.8835918668. The cubic root of 66600021 is about 405.3449705193.

Adding to 66600021 its reverse (12000666), we get a palindrome (78600687).

The spelling of 66600021 in words is "sixty-six million, six hundred thousand, twenty-one".