66978511794 has 16 divisors (see below), whose sum is σ = 148841137440. Its totient is φ = 22326170580.

The previous prime is 66978511763. The next prime is 66978511913. The reversal of 66978511794 is 49711587966.

It is a super-3 number, since 3×66978511794³ (a number of 33 digits) contains 333 as substring. Note that it is a super-d number also for d = 2.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 620171352 + ... + 620171459.

It is an arithmetic number, because the mean of its divisors is an integer number (9302571090).

Almost surely, 2^66978511794 is an apocalyptic number.

66978511794 is an abundant number, since it is smaller than the sum of its proper divisors (81862625646).

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

66978511794 is a wasteful number, since it uses less digits than its factorization.

66978511794 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1240342822 (or 1240342816 counting only the distinct ones).

The product of its digits is 22861440, while the sum is 63.

The spelling of 66978511794 in words is "sixty-six billion, nine hundred seventy-eight million, five hundred eleven thousand, seven hundred ninety-four".