66721144 has 24 divisors (see below), whose sum is σ = 145527840. Its totient is φ = 28594608.

The previous prime is 66721139. The next prime is 66721169. The reversal of 66721144 is 44112766.

It is a super-2 number, since 2×66721144² = 8903422113337472, which contains 22 as substring.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 84712 + ... + 85495.

It is an arithmetic number, because the mean of its divisors is an integer number (6063660).

Almost surely, 2^66721144 is an apocalyptic number.

It is an amenable number.

66721144 is an abundant number, since it is smaller than the sum of its proper divisors (78806696).

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

66721144 is a wasteful number, since it uses less digits than its factorization.

66721144 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 170227 (or 170216 counting only the distinct ones).

The product of its digits is 8064, while the sum is 31.

The square root of 66721144 is about 8168.3011697660. The cubic root of 66721144 is about 405.5905503493.

The spelling of 66721144 in words is "sixty-six million, seven hundred twenty-one thousand, one hundred forty-four".