66921905 has 8 divisors (see below), whose sum is σ = 80352384. Its totient is φ = 53506800.

The previous prime is 66921887. The next prime is 66921917. The reversal of 66921905 is 50912966.

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

It is not a de Polignac number, because 66921905 - 2¹⁰ = 66920881 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 10850 + ... + 15860.

It is an arithmetic number, because the mean of its divisors is an integer number (10044048).

Almost surely, 2^66921905 is an apocalyptic number.

It is an amenable number.

66921905 is a deficient number, since it is larger than the sum of its proper divisors (13430479).

66921905 is a wasteful number, since it uses less digits than its factorization.

66921905 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 7687.

The product of its (nonzero) digits is 29160, while the sum is 38.

The square root of 66921905 is about 8180.5809695889. The cubic root of 66921905 is about 405.9969444147.

The spelling of 66921905 in words is "sixty-six million, nine hundred twenty-one thousand, nine hundred five".