1643226661 has 8 divisors (see below), whose sum is σ = 1650953664. Its totient is φ = 1635516960.

The previous prime is 1643226631. The next prime is 1643226667. The reversal of 1643226661 is 1666223461.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-1643226661 is a prime.

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 1643226661.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1643226667) 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, 210321 + ... + 217993.

It is an arithmetic number, because the mean of its divisors is an integer number (206369208).

Almost surely, 2^1643226661 is an apocalyptic number.

It is an amenable number.

1643226661 is a deficient number, since it is larger than the sum of its proper divisors (7727003).

1643226661 is an equidigital number, since it uses as much as digits as its factorization.

1643226661 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 8651.

The product of its digits is 62208, while the sum is 37.

The square root of 1643226661 is about 40536.7322437317. The cubic root of 1643226661 is about 1180.0465989928.

The spelling of 1643226661 in words is "one billion, six hundred forty-three million, two hundred twenty-six thousand, six hundred sixty-one".