665453881 has 4 divisors (see below), whose sum is σ = 665512564. Its totient is φ = 665395200.

The previous prime is 665453869. The next prime is 665453947. The reversal of 665453881 is 188354566.

It is a semiprime because it is the product of two primes, and also a brilliant number, because the two primes have the same length, and also an emirpimes, since its reverse is a distinct semiprime: 188354566 = 2 ⋅94177283.

It can be written as a sum of positive squares in 2 ways, for example, as 551498256 + 113955625 = 23484^2 + 10675^2 .

It is a cyclic number.

It is not a de Polignac number, because 665453881 - 2¹⁷ = 665322809 is a prime.

It is a super-2 number, since 2×665453881² = 885657735475924322, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (665453281) 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, 6300 + ... + 37021.

It is an arithmetic number, because the mean of its divisors is an integer number (166378141).

It is a 11340-hyperperfect number.

Almost surely, 2^665453881 is an apocalyptic number.

It is an amenable number.

665453881 is a deficient number, since it is larger than the sum of its proper divisors (58683).

665453881 is a wasteful number, since it uses less digits than its factorization.

665453881 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 58682.

The product of its digits is 691200, while the sum is 46.

The square root of 665453881 is about 25796.3927904659. The cubic root of 665453881 is about 873.0504102518.

The spelling of 665453881 in words is "six hundred sixty-five million, four hundred fifty-three thousand, eight hundred eighty-one".