665873421 has 8 divisors (see below), whose sum is σ = 888483360. Its totient is φ = 443589552.

The previous prime is 665873407. The next prime is 665873443. The reversal of 665873421 is 124378566.

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

It is not a de Polignac number, because 665873421 - 2¹¹ = 665871373 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (665873491) 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, 76711 + ... + 84948.

It is an arithmetic number, because the mean of its divisors is an integer number (111060420).

Almost surely, 2^665873421 is an apocalyptic number.

It is an amenable number.

665873421 is a deficient number, since it is larger than the sum of its proper divisors (222609939).

665873421 is a wasteful number, since it uses less digits than its factorization.

665873421 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 163035.

The product of its digits is 241920, while the sum is 42.

The square root of 665873421 is about 25804.5232662803. The cubic root of 665873421 is about 873.2338452637.

The spelling of 665873421 in words is "six hundred sixty-five million, eight hundred seventy-three thousand, four hundred twenty-one".