666978624 has 168 divisors, whose sum is σ = 2135733600. Its totient is φ = 205161984.

The previous prime is 666978617. The next prime is 666978643. The reversal of 666978624 is 426879666.

It is a Smith number, since the sum of its digits (54) coincides with the sum of the digits of its prime factors.

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 (11) of ones.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 200527 + ... + 203825.

It is an arithmetic number, because the mean of its divisors is an integer number (12712700).

Almost surely, 2^666978624 is an apocalyptic number.

666978624 is a gapful number since it is divisible by the number (64) 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 666978624, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1067866800).

666978624 is an abundant number, since it is smaller than the sum of its proper divisors (1468754976).

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

666978624 is a wasteful number, since it uses less digits than its factorization.

666978624 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3339 (or 3317 counting only the distinct ones).

The product of its digits is 5225472, while the sum is 54.

The square root of 666978624 is about 25825.9292959615. The cubic root of 666978624 is about 873.7167034043.

The spelling of 666978624 in words is "six hundred sixty-six million, nine hundred seventy-eight thousand, six hundred twenty-four".