665779481 has 4 divisors (see below), whose sum is σ = 678341412. Its totient is φ = 653217552.

The previous prime is 665779463. The next prime is 665779507. The reversal of 665779481 is 184977566.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 184977566 = 2 ⋅92488783.

It can be written as a sum of positive squares in 2 ways, for example, as 219513856 + 446265625 = 14816^2 + 21125^2 .

It is a cyclic number.

It is not a de Polignac number, because 665779481 - 2¹⁰ = 665778457 is a prime.

It is a super-2 number, since 2×665779481² = 886524634641258722, which contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (53), and also a Moran number because the ratio is a prime number: 12561877 = 665779481 / (6 + 6 + 5 + 7 + 7 + 9 + 4 + 8 + 1).

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (665779421) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 6280886 + ... + 6280991.

It is an arithmetic number, because the mean of its divisors is an integer number (169585353).

Almost surely, 2^665779481 is an apocalyptic number.

It is an amenable number.

665779481 is a deficient number, since it is larger than the sum of its proper divisors (12561931).

665779481 is a wasteful number, since it uses less digits than its factorization.

665779481 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 12561930.

The product of its digits is 2540160, while the sum is 53.

The square root of 665779481 is about 25802.7029785641. The cubic root of 665779481 is about 873.1927786772.

The spelling of 665779481 in words is "six hundred sixty-five million, seven hundred seventy-nine thousand, four hundred eighty-one".