665405551 has 8 divisors (see below), whose sum is σ = 728842320. Its totient is φ = 604668288.

The previous prime is 665405549. The next prime is 665405561. The reversal of 665405551 is 155504566.

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 665405551 - 2¹ = 665405549 is a prime.

It is a super-2 number, since 2×665405551² = 885529094603227202, which contains 22 as substring.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 665405551.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (665405561) 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, 674361 + ... + 675346.

It is an arithmetic number, because the mean of its divisors is an integer number (91105290).

Almost surely, 2^665405551 is an apocalyptic number.

665405551 is a deficient number, since it is larger than the sum of its proper divisors (63436769).

665405551 is a wasteful number, since it uses less digits than its factorization.

665405551 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1349753.

The product of its (nonzero) digits is 90000, while the sum is 37.

The square root of 665405551 is about 25795.4560145775. The cubic root of 665405551 is about 873.0292740274.

The spelling of 665405551 in words is "six hundred sixty-five million, four hundred five thousand, five hundred fifty-one".