66561728078 has 8 divisors (see below), whose sum is σ = 99958287168. Its totient is φ = 33242299024.

The previous prime is 66561728069. The next prime is 66561728099. The reversal of 66561728078 is 87082716566.

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

It is a super-2 number, since 2×66561728078² (a number of 22 digits) contains 22 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, 19280351 + ... + 19283802.

It is an arithmetic number, because the mean of its divisors is an integer number (12494785896).

Almost surely, 2^66561728078 is an apocalyptic number.

66561728078 is a deficient number, since it is larger than the sum of its proper divisors (33396559090).

66561728078 is a wasteful number, since it uses less digits than its factorization.

66561728078 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 38565018.

The product of its (nonzero) digits is 6773760, while the sum is 56.

The spelling of 66561728078 in words is "sixty-six billion, five hundred sixty-one million, seven hundred twenty-eight thousand, seventy-eight".