66891028 has 24 divisors (see below), whose sum is σ = 119585088. Its totient is φ = 32731776.

The previous prime is 66890983. The next prime is 66891043. The reversal of 66891028 is 82019866.

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, 36625 + ... + 38407.

It is an arithmetic number, because the mean of its divisors is an integer number (4982712).

Almost surely, 2^66891028 is an apocalyptic number.

It is an amenable number.

66891028 is a deficient number, since it is larger than the sum of its proper divisors (52694060).

66891028 is a wasteful number, since it uses less digits than its factorization.

66891028 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1983 (or 1981 counting only the distinct ones).

The product of its (nonzero) digits is 41472, while the sum is 40.

The square root of 66891028 is about 8178.6935387016. The cubic root of 66891028 is about 405.9344940300.

The spelling of 66891028 in words is "sixty-six million, eight hundred ninety-one thousand, twenty-eight".