66721958 has 16 divisors (see below), whose sum is σ = 106379520. Its totient is φ = 31296456.

The previous prime is 66721943. The next prime is 66721961. The reversal of 66721958 is 85912766.

It is a Curzon number.

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, 4610 + ... + 12437.

It is an arithmetic number, because the mean of its divisors is an integer number (6648720).

Almost surely, 2^66721958 is an apocalyptic number.

66721958 is a deficient number, since it is larger than the sum of its proper divisors (39657562).

66721958 is a wasteful number, since it uses less digits than its factorization.

66721958 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 17171.

The product of its digits is 181440, while the sum is 44.

The square root of 66721958 is about 8168.3509963762. The cubic root of 66721958 is about 405.5921997483.

The spelling of 66721958 in words is "sixty-six million, seven hundred twenty-one thousand, nine hundred fifty-eight".