66784981 has 8 divisors (see below), whose sum is σ = 70398720. Its totient is φ = 63181152.

The previous prime is 66784973. The next prime is 66784987. The reversal of 66784981 is 18948766.

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

It is a cyclic number.

It is not a de Polignac number, because 66784981 - 2³ = 66784973 is a prime.

It is a super-2 number, since 2×66784981² = 8920467374340722, which contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (66784987) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 14361 + ... + 18433.

It is an arithmetic number, because the mean of its divisors is an integer number (8799840).

Almost surely, 2^66784981 is an apocalyptic number.

It is an amenable number.

66784981 is a deficient number, since it is larger than the sum of its proper divisors (3613739).

66784981 is a wasteful number, since it uses less digits than its factorization.

66784981 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4955.

The product of its digits is 580608, while the sum is 49.

The square root of 66784981 is about 8172.2078412140. The cubic root of 66784981 is about 405.7198618354.

The spelling of 66784981 in words is "sixty-six million, seven hundred eighty-four thousand, nine hundred eighty-one".