66891878 has 8 divisors (see below), whose sum is σ = 100491600. Its totient is φ = 33394680.

The previous prime is 66891863. The next prime is 66891887. The reversal of 66891878 is 87819866.

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

It is a super-4 number, since 4×66891878⁴ (a number of 32 digits) contains 4444 as substring.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 23978 + ... + 26621.

It is an arithmetic number, because the mean of its divisors is an integer number (12561450).

Almost surely, 2^66891878 is an apocalyptic number.

66891878 is a deficient number, since it is larger than the sum of its proper divisors (33599722).

66891878 is a wasteful number, since it uses less digits than its factorization.

66891878 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 51262.

The product of its digits is 1161216, while the sum is 53.

The square root of 66891878 is about 8178.7455028262. The cubic root of 66891878 is about 405.9362134577.

The spelling of 66891878 in words is "sixty-six million, eight hundred ninety-one thousand, eight hundred seventy-eight".