665867551 has 8 divisors (see below), whose sum is σ = 671838464. Its totient is φ = 659919960.

The previous prime is 665867491. The next prime is 665867557. The reversal of 665867551 is 155768566.

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 665867551 - 2¹⁵ = 665834783 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 665867495 and 665867504.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (665867557) 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, 54256 + ... + 65386.

It is an arithmetic number, because the mean of its divisors is an integer number (83979808).

Almost surely, 2^665867551 is an apocalyptic number.

665867551 is a deficient number, since it is larger than the sum of its proper divisors (5970913).

665867551 is a wasteful number, since it uses less digits than its factorization.

665867551 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 11661.

The product of its digits is 1512000, while the sum is 49.

The square root of 665867551 is about 25804.4095262806. The cubic root of 665867551 is about 873.2312792616.

The spelling of 665867551 in words is "six hundred sixty-five million, eight hundred sixty-seven thousand, five hundred fifty-one".