6665221549 has 4 divisors (see below), whose sum is σ = 7617396064. Its totient is φ = 5713047036.

The previous prime is 6665221517. The next prime is 6665221571. The reversal of 6665221549 is 9451225666.

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: 9451225666 = 2 ⋅4725612833.

It is a cyclic number.

It is not a de Polignac number, because 6665221549 - 2⁵ = 6665221517 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 6665221499 and 6665221508.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (6665221349) 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, 476087247 + ... + 476087260.

It is an arithmetic number, because the mean of its divisors is an integer number (1904349016).

Almost surely, 2^6665221549 is an apocalyptic number.

It is an amenable number.

6665221549 is a deficient number, since it is larger than the sum of its proper divisors (952174515).

6665221549 is an equidigital number, since it uses as much as digits as its factorization.

6665221549 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 952174514.

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

The square root of 6665221549 is about 81640.8081108951. The cubic root of 6665221549 is about 1881.9360571557.

The spelling of 6665221549 in words is "six billion, six hundred sixty-five million, two hundred twenty-one thousand, five hundred forty-nine".