66896721 has 12 divisors (see below), whose sum is σ = 97533072. Its totient is φ = 44180376.

The previous prime is 66896699. The next prime is 66896723. The reversal of 66896721 is 12769866.

It is not a de Polignac number, because 66896721 - 2⁶ = 66896657 is a prime.

It is not an unprimeable number, because it can be changed into a prime (66896723) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 33771 + ... + 35696.

It is an arithmetic number, because the mean of its divisors is an integer number (8127756).

Almost surely, 2^66896721 is an apocalyptic number.

It is an amenable number.

66896721 is a deficient number, since it is larger than the sum of its proper divisors (30636351).

66896721 is a wasteful number, since it uses less digits than its factorization.

66896721 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 69580 (or 69577 counting only the distinct ones).

The product of its digits is 217728, while the sum is 45.

The square root of 66896721 is about 8179.0415697684. The cubic root of 66896721 is about 405.9460098720.

The spelling of 66896721 in words is "sixty-six million, eight hundred ninety-six thousand, seven hundred twenty-one".