66978100 has 54 divisors (see below), whose sum is σ = 169084230. Its totient is φ = 22962240.

The previous prime is 66978089. The next prime is 66978101. The reversal of 66978100 is 187966.

66978100 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It can be written as a sum of positive squares in 3 ways, for example, as 9400356 + 57577744 = 3066^2 + 7588^2 .

It is a super-2 number, since 2×66978100² = 8972131759220000, which contains 22 as substring.

It is a self number, because there is not a number n which added to its sum of digits gives 66978100.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (66978101) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 17 ways as a sum of consecutive naturals, for example, 1935 + ... + 11734.

Almost surely, 2^66978100 is an apocalyptic number.

It is an amenable number.

66978100 is an abundant number, since it is smaller than the sum of its proper divisors (102106130).

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

66978100 is a wasteful number, since it uses less digits than its factorization.

66978100 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 13697 (or 13683 counting only the distinct ones).

The product of its (nonzero) digits is 18144, while the sum is 37.

The square root of 66978100 is about 8184.0149071223. The cubic root of 66978100 is about 406.1105525339.

The spelling of 66978100 in words is "sixty-six million, nine hundred seventy-eight thousand, one hundred".