66516881 has 4 divisors (see below), whose sum is σ = 66627072. Its totient is φ = 66406692.

The previous prime is 66516839. The next prime is 66516889. The reversal of 66516881 is 18861566.

It is a happy number.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 66516881 - 2⁶ = 66516817 is a prime.

It is a super-2 number, since 2×66516881² = 8848990915936322, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (66516889) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 54185 + ... + 55398.

It is an arithmetic number, because the mean of its divisors is an integer number (16656768).

Almost surely, 2^66516881 is an apocalyptic number.

It is an amenable number.

66516881 is a deficient number, since it is larger than the sum of its proper divisors (110191).

66516881 is a wasteful number, since it uses less digits than its factorization.

66516881 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 110190.

The product of its digits is 69120, while the sum is 41.

The square root of 66516881 is about 8155.7881899912. The cubic root of 66516881 is about 405.1762297625.

The spelling of 66516881 in words is "sixty-six million, five hundred sixteen thousand, eight hundred eighty-one".