66128798454778 has 8 divisors (see below), whose sum is σ = 99322187538420. Its totient is φ = 33021402608640.

The previous prime is 66128798454751. The next prime is 66128798454833. The reversal of 66128798454778 is 87745489782166.

It can be written as a sum of positive squares in 2 ways, for example, as 66108721548529 + 20076906249 = 8130727^2 + 141693^2 .

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

It is a super-2 number, since 2×66128798454778² (a number of 28 digits) contains 22 as substring.

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, 21498307453 + ... + 21498310528.

Almost surely, 2^{66128798454778} is an apocalyptic number.

66128798454778 is a deficient number, since it is larger than the sum of its proper divisors (33193389083642).

66128798454778 is a wasteful number, since it uses less digits than its factorization.

66128798454778 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 42996618752.

The product of its digits is 9103933440, while the sum is 82.

The spelling of 66128798454778 in words is "sixty-six trillion, one hundred twenty-eight billion, seven hundred ninety-eight million, four hundred fifty-four thousand, seven hundred seventy-eight".