66551677920 has 1536 divisors, whose sum is σ = 305198530560. Its totient is φ = 13168189440.

The previous prime is 66551677861. The next prime is 66551677957. The reversal of 66551677920 is 2977615566.

66551677920 is a `hidden beast` number, since 6 + 6 + 551 + 67 + 7 + 9 + 20 = 666.

It is a Harshad number since it is a multiple of its sum of digits (54).

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 255 ways as a sum of consecutive naturals, for example, 524028897 + ... + 524029023.

It is an arithmetic number, because the mean of its divisors is an integer number (198696960).

Almost surely, 2^66551677920 is an apocalyptic number.

66551677920 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 66551677920, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (152599265280).

66551677920 is an abundant number, since it is smaller than the sum of its proper divisors (238646852640).

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

66551677920 is a wasteful number, since it uses less digits than its factorization.

66551677920 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 245 (or 231 counting only the distinct ones).

The product of its (nonzero) digits is 4762800, while the sum is 54.

The spelling of 66551677920 in words is "sixty-six billion, five hundred fifty-one million, six hundred seventy-seven thousand, nine hundred twenty".