66778388 has 12 divisors (see below), whose sum is σ = 123012960. Its totient is φ = 31631832.

The previous prime is 66778351. The next prime is 66778417. The reversal of 66778388 is 88387766.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 439256 + ... + 439407.

It is an arithmetic number, because the mean of its divisors is an integer number (10251080).

Almost surely, 2^66778388 is an apocalyptic number.

It is an amenable number.

66778388 is a deficient number, since it is larger than the sum of its proper divisors (56234572).

66778388 is a wasteful number, since it uses less digits than its factorization.

66778388 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 878686 (or 878684 counting only the distinct ones).

The product of its digits is 2709504, while the sum is 53.

The square root of 66778388 is about 8171.8044518943. The cubic root of 66778388 is about 405.7065105348.

The spelling of 66778388 in words is "sixty-six million, seven hundred seventy-eight thousand, three hundred eighty-eight".