66778840 has 16 divisors (see below), whose sum is σ = 150252480. Its totient is φ = 26711520.

The previous prime is 66778799. The next prime is 66778841. The reversal of 66778840 is 4887766.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (66778841) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 834696 + ... + 834775.

It is an arithmetic number, because the mean of its divisors is an integer number (9390780).

Almost surely, 2^66778840 is an apocalyptic number.

It is an amenable number.

66778840 is an abundant number, since it is smaller than the sum of its proper divisors (83473640).

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

66778840 is a wasteful number, since it uses less digits than its factorization.

66778840 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1669482 (or 1669478 counting only the distinct ones).

The product of its (nonzero) digits is 451584, while the sum is 46.

The square root of 66778840 is about 8171.8321079180. The cubic root of 66778840 is about 405.7074258955.

It can be divided in two parts, 667 and 78840, that added together give a cube (79507 = 43³).

The spelling of 66778840 in words is "sixty-six million, seven hundred seventy-eight thousand, eight hundred forty".