66921906 has 8 divisors (see below), whose sum is σ = 133843824. Its totient is φ = 22307300.

The previous prime is 66921887. The next prime is 66921917. The reversal of 66921906 is 60912966.

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

66921906 is an admirable number.

It is a Curzon number.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 5576820 + ... + 5576831.

It is an arithmetic number, because the mean of its divisors is an integer number (16730478).

Almost surely, 2^66921906 is an apocalyptic number.

66921906 is a primitive abundant number, since it is smaller than the sum of its proper divisors, none of which is abundant.

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

66921906 is a wasteful number, since it uses less digits than its factorization.

66921906 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 11153656.

The product of its (nonzero) digits is 34992, while the sum is 39.

The square root of 66921906 is about 8180.5810307092. The cubic root of 66921906 is about 405.9969464369.

The spelling of 66921906 in words is "sixty-six million, nine hundred twenty-one thousand, nine hundred six".