66979781069 has 4 divisors (see below), whose sum is σ = 69140419200. Its totient is φ = 64819142940.

The previous prime is 66979781053. The next prime is 66979781107. The reversal of 66979781069 is 96018797966.

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 66979781069 - 2⁴ = 66979781053 is a prime.

It is a super-2 number, since 2×66979781069² (a number of 22 digits) 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 (66979721069) 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, 1080319019 + ... + 1080319080.

It is an arithmetic number, because the mean of its divisors is an integer number (17285104800).

Almost surely, 2^66979781069 is an apocalyptic number.

It is an amenable number.

66979781069 is a deficient number, since it is larger than the sum of its proper divisors (2160638131).

66979781069 is a wasteful number, since it uses less digits than its factorization.

66979781069 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2160638130.

The product of its (nonzero) digits is 61725888, while the sum is 68.

The spelling of 66979781069 in words is "sixty-six billion, nine hundred seventy-nine million, seven hundred eighty-one thousand, sixty-nine".