665889281 has 8 divisors (see below), whose sum is σ = 681498240. Its totient is φ = 650424528.

The previous prime is 665889277. The next prime is 665889299. The reversal of 665889281 is 182988566.

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

It is a cyclic number.

It is not a de Polignac number, because 665889281 - 2² = 665889277 is a prime.

It is a super-2 number, since 2×665889281² = 886817069101393922, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (665889251) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 26681 + ... + 45206.

It is an arithmetic number, because the mean of its divisors is an integer number (85187280).

Almost surely, 2^665889281 is an apocalyptic number.

It is an amenable number.

665889281 is a deficient number, since it is larger than the sum of its proper divisors (15608959).

665889281 is a wasteful number, since it uses less digits than its factorization.

665889281 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 72103.

The product of its digits is 1658880, while the sum is 53.

The square root of 665889281 is about 25804.8305749137. The cubic root of 665889281 is about 873.2407782024.

The spelling of 665889281 in words is "six hundred sixty-five million, eight hundred eighty-nine thousand, two hundred eighty-one".