66278617920 has 672 divisors, whose sum is σ = 247634150400. Its totient is φ = 16228270080.

The previous prime is 66278617903. The next prime is 66278617939. The reversal of 66278617920 is 2971687266.

66278617920 is a `hidden beast` number, since 6 + 627 + 8 + 6 + 1 + 7 + 9 + 2 + 0 = 666.

66278617920 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 95 ways as a sum of consecutive naturals, for example, 189909906 + ... + 189910254.

It is an arithmetic number, because the mean of its divisors is an integer number (368503200).

Almost surely, 2^66278617920 is an apocalyptic number.

66278617920 is a gapful number since it is divisible by the number (60) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 66278617920, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (123817075200).

66278617920 is an abundant number, since it is smaller than the sum of its proper divisors (181355532480).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

66278617920 is a wasteful number, since it uses less digits than its factorization.

66278617920 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 503 (or 490 counting only the distinct ones).

The product of its (nonzero) digits is 3048192, while the sum is 54.

The spelling of 66278617920 in words is "sixty-six billion, two hundred seventy-eight million, six hundred seventeen thousand, nine hundred twenty".