66378111961 has 8 divisors (see below), whose sum is σ = 75965052800. Its totient is φ = 56817259488.

The previous prime is 66378111949. The next prime is 66378111997. The reversal of 66378111961 is 16911187366.

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

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-66378111961 is a prime.

It is the 257640-th Hogben number.

It is not an unprimeable number, because it can be changed into a prime (66378111931) by changing a digit.

It is a nontrivial repunit in base 257639.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 6516636 + ... + 6526813.

It is an arithmetic number, because the mean of its divisors is an integer number (9495631600).

Almost surely, 2^66378111961 is an apocalyptic number.

It is an amenable number.

66378111961 is a deficient number, since it is larger than the sum of its proper divisors (9586940839).

66378111961 is a wasteful number, since it uses less digits than its factorization.

66378111961 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 13044183.

The product of its digits is 326592, while the sum is 49.

The spelling of 66378111961 in words is "sixty-six billion, three hundred seventy-eight million, one hundred eleven thousand, nine hundred sixty-one".