665156449 has 4 divisors (see below), whose sum is σ = 666593536. Its totient is φ = 663719364.

The previous prime is 665156431. The next prime is 665156461. The reversal of 665156449 is 944651566.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4, and also an emirpimes, since its reverse is a distinct semiprime: 944651566 = 2 ⋅472325783.

It is a cyclic number.

It is not a de Polignac number, because 665156449 - 2⁹ = 665155937 is a prime.

It is a super-3 number, since 3×665156449³ (a number of 27 digits) contains 333 as substring.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 665156399 and 665156408.

It is not an unprimeable number, because it can be changed into a prime (665156249) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 717849 + ... + 718774.

It is an arithmetic number, because the mean of its divisors is an integer number (166648384).

Almost surely, 2^665156449 is an apocalyptic number.

It is an amenable number.

665156449 is a deficient number, since it is larger than the sum of its proper divisors (1437087).

665156449 is a wasteful number, since it uses less digits than its factorization.

665156449 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1437086.

The product of its digits is 777600, while the sum is 46.

The square root of 665156449 is about 25790.6271540651. The cubic root of 665156449 is about 872.9203176766.

It can be divided in two parts, 66 and 5156449, that added together give a palindrome (5156515).

The spelling of 665156449 in words is "six hundred sixty-five million, one hundred fifty-six thousand, four hundred forty-nine".