66821875 has 12 divisors (see below), whose sum is σ = 83525904. Its totient is φ = 53455000.

The previous prime is 66821857. The next prime is 66821891. The reversal of 66821875 is 57812866.

It is a de Polignac number, because none of the positive numbers 2^k-66821875 is a prime.

It is a Duffinian number.

It is an unprimeable number.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 7567 + ... + 13816.

It is an arithmetic number, because the mean of its divisors is an integer number (6960492).

Almost surely, 2^66821875 is an apocalyptic number.

66821875 is a deficient number, since it is larger than the sum of its proper divisors (16704029).

66821875 is an frugal number, since it uses more digits than its factorization.

66821875 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 21408 (or 21388 counting only the distinct ones).

The product of its digits is 161280, while the sum is 43.

The square root of 66821875 is about 8174.4648142860. The cubic root of 66821875 is about 405.7945586352.

Subtracting from 66821875 its reverse (57812866), we obtain a palindrome (9009009).

The spelling of 66821875 in words is "sixty-six million, eight hundred twenty-one thousand, eight hundred seventy-five".