66978648 has 96 divisors (see below), whose sum is σ = 208353600. Its totient is φ = 19224000.

The previous prime is 66978581. The next prime is 66978673. The reversal of 66978648 is 84687966.

It is a super-2 number, since 2×66978648² = 8972278575815808, which contains 22 as substring.

It is a junction number, because it is equal to n+sod(n) for n = 66978594 and 66978603.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 12823 + ... + 17273.

It is an arithmetic number, because the mean of its divisors is an integer number (2170350).

Almost surely, 2^66978648 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 66978648, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (104176800).

66978648 is an abundant number, since it is smaller than the sum of its proper divisors (141374952).

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

66978648 is a wasteful number, since it uses less digits than its factorization.

66978648 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4493 (or 4486 counting only the distinct ones).

The product of its digits is 3483648, while the sum is 54.

The square root of 66978648 is about 8184.0483869537. The cubic root of 66978648 is about 406.1116600998. Note that the first 3 decimals are identical.

It can be divided in two parts, 66978 and 648, that multiplied together give a square (43401744 = 6588²).

The spelling of 66978648 in words is "sixty-six million, nine hundred seventy-eight thousand, six hundred forty-eight".