666721598 has 8 divisors (see below), whose sum is σ = 1004822760. Its totient is φ = 331780680.

The previous prime is 666721591. The next prime is 666721603. The reversal of 666721598 is 895127666.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (666721591) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 789533 + ... + 790376.

It is an arithmetic number, because the mean of its divisors is an integer number (125602845).

Almost surely, 2^666721598 is an apocalyptic number.

666721598 is a deficient number, since it is larger than the sum of its proper divisors (338101162).

666721598 is a wasteful number, since it uses less digits than its factorization.

666721598 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1580122.

The product of its digits is 1088640, while the sum is 50.

The square root of 666721598 is about 25820.9526935007. The cubic root of 666721598 is about 873.6044575472.

The spelling of 666721598 in words is "six hundred sixty-six million, seven hundred twenty-one thousand, five hundred ninety-eight".