66666757920 has 288 divisors, whose sum is σ = 244617081408. Its totient is φ = 15217477632.

The previous prime is 66666757873. The next prime is 66666757943. The reversal of 66666757920 is 2975766666.

It is a super-2 number, since 2×66666757920² (a number of 22 digits) contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (60).

It is an unprimeable number.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 23448019 + ... + 23450861.

It is an arithmetic number, because the mean of its divisors is an integer number (849364866).

Almost surely, 2^66666757920 is an apocalyptic number.

66666757920 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 66666757920, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (122308540704).

66666757920 is an abundant number, since it is smaller than the sum of its proper divisors (177950323488).

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

66666757920 is a wasteful number, since it uses less digits than its factorization.

66666757920 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3872 (or 3857 counting only the distinct ones).

The product of its (nonzero) digits is 34292160, while the sum is 60.

The spelling of 66666757920 in words is "sixty-six billion, six hundred sixty-six million, seven hundred fifty-seven thousand, nine hundred twenty".