66775921 has 8 divisors (see below), whose sum is σ = 68544000. Its totient is φ = 65014560.

The previous prime is 66775913. The next prime is 66775927. The reversal of 66775921 is 12957766.

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 66775921 - 2³ = 66775913 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (66775927) 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, 23200 + ... + 25918.

It is an arithmetic number, because the mean of its divisors is an integer number (8568000).

Almost surely, 2^66775921 is an apocalyptic number.

It is an amenable number.

66775921 is a deficient number, since it is larger than the sum of its proper divisors (1768079).

66775921 is a wasteful number, since it uses less digits than its factorization.

66775921 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3359.

The product of its digits is 158760, while the sum is 43.

The square root of 66775921 is about 8171.6535046464. The cubic root of 66775921 is about 405.7015144559.

The spelling of 66775921 in words is "sixty-six million, seven hundred seventy-five thousand, nine hundred twenty-one".