66808881 has 10 divisors (see below), whose sum is σ = 99801042. Its totient is φ = 44539200.

The previous prime is 66808871. The next prime is 66808891. The reversal of 66808881 is 18880866.

It is a happy number.

It is an interprime number because it is at equal distance from previous prime (66808871) and next prime (66808891).

It can be written as a sum of positive squares in only one way, i.e., 66341025 + 467856 = 8145^2 + 684^2 .

It is not a de Polignac number, because 66808881 - 2¹¹ = 66806833 is a prime.

It is a super-2 number, since 2×66808881² = 8926853160944322, which contains 22 as substring.

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (66808831) by changing a digit.

It is a polite number, since it can be written in 9 ways as a sum of consecutive naturals, for example, 412320 + ... + 412481.

Almost surely, 2^66808881 is an apocalyptic number.

It is an amenable number.

66808881 is a deficient number, since it is larger than the sum of its proper divisors (32992161).

66808881 is an equidigital number, since it uses as much as digits as its factorization.

66808881 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 824813 (or 824804 counting only the distinct ones).

The product of its (nonzero) digits is 147456, while the sum is 45.

The square root of 66808881 is about 8173.6699835508. The cubic root of 66808881 is about 405.7682536948.

The spelling of 66808881 in words is "sixty-six million, eight hundred eight thousand, eight hundred eighty-one".