66616881 has 8 divisors (see below), whose sum is σ = 88904160. Its totient is φ = 44370432.

The previous prime is 66616871. The next prime is 66616883. The reversal of 66616881 is 18861666.

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

It is not a de Polignac number, because 66616881 - 2¹¹ = 66614833 is a prime.

It is a super-2 number, since 2×66616881² = 8875617668336322, which contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (66616883) 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, 6171 + ... + 13088.

It is an arithmetic number, because the mean of its divisors is an integer number (11113020).

Almost surely, 2^66616881 is an apocalyptic number.

It is an amenable number.

66616881 is a deficient number, since it is larger than the sum of its proper divisors (22287279).

66616881 is a wasteful number, since it uses less digits than its factorization.

66616881 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 20415.

The product of its digits is 82944, while the sum is 42.

The square root of 66616881 is about 8161.9165028809. The cubic root of 66616881 is about 405.3791724084.

The spelling of 66616881 in words is "sixty-six million, six hundred sixteen thousand, eight hundred eighty-one".