66421805 has 8 divisors (see below), whose sum is σ = 84394872. Its totient is φ = 50011648.

The previous prime is 66421801. The next prime is 66421807. The reversal of 66421805 is 50812466.

It can be written as a sum of positive squares in 4 ways, for example, as 20967241 + 45454564 = 4579^2 + 6742^2 .

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 66421805 - 2² = 66421801 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (66421801) 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, 390632 + ... + 390801.

It is an arithmetic number, because the mean of its divisors is an integer number (10549359).

Almost surely, 2^66421805 is an apocalyptic number.

It is an amenable number.

66421805 is a deficient number, since it is larger than the sum of its proper divisors (17973067).

66421805 is a wasteful number, since it uses less digits than its factorization.

66421805 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 781455.

The product of its (nonzero) digits is 11520, while the sum is 32.

The square root of 66421805 is about 8149.9573618517. The cubic root of 66421805 is about 404.9830913024.

The spelling of 66421805 in words is "sixty-six million, four hundred twenty-one thousand, eight hundred five".