66978605 has 8 divisors (see below), whose sum is σ = 80562552. Its totient is φ = 53457408.

The previous prime is 66978581. The next prime is 66978673. The reversal of 66978605 is 50687966.

It can be written as a sum of positive squares in 4 ways, for example, as 946729 + 66031876 = 973^2 + 8126^2 .

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 66978605 - 2¹⁴ = 66962221 is a prime.

It is a super-2 number, since 2×66978605² = 8972267055492050, which contains 22 as substring.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 66978605.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 13304 + ... + 17633.

It is an arithmetic number, because the mean of its divisors is an integer number (10070319).

Almost surely, 2^66978605 is an apocalyptic number.

It is an amenable number.

66978605 is a deficient number, since it is larger than the sum of its proper divisors (13583947).

66978605 is a wasteful number, since it uses less digits than its factorization.

66978605 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 31375.

The product of its (nonzero) digits is 544320, while the sum is 47.

The square root of 66978605 is about 8184.0457598916. The cubic root of 66978605 is about 406.1115731924. Note that the first 3 decimals are identical.

The spelling of 66978605 in words is "sixty-six million, nine hundred seventy-eight thousand, six hundred five".