66991144 has 16 divisors (see below), whose sum is σ = 137027520. Its totient is φ = 30450480.

The previous prime is 66991117. The next prime is 66991163. The reversal of 66991144 is 44119966.

It is a zygodrome in base 10.

It is a junction number, because it is equal to n+sod(n) for n = 66991097 and 66991106.

It is an unprimeable number.

It is an upside-down number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 380544 + ... + 380719.

It is an arithmetic number, because the mean of its divisors is an integer number (8564220).

Almost surely, 2^66991144 is an apocalyptic number.

It is an amenable number.

66991144 is an abundant number, since it is smaller than the sum of its proper divisors (70036376).

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

66991144 is a wasteful number, since it uses less digits than its factorization.

66991144 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 761280 (or 761276 counting only the distinct ones).

The product of its digits is 46656, while the sum is 40.

The square root of 66991144 is about 8184.8117876955. The cubic root of 66991144 is about 406.1369141964.

The spelling of 66991144 in words is "sixty-six million, nine hundred ninety-one thousand, one hundred forty-four".