1620221663 has 4 divisors (see below), whose sum is σ = 1620550008. Its totient is φ = 1619893320.

The previous prime is 1620221623. The next prime is 1620221693. The reversal of 1620221663 is 3661220261.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 1620221663 - 2¹⁶ = 1620156127 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1620221623) 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, 156656 + ... + 166677.

It is an arithmetic number, because the mean of its divisors is an integer number (405137502).

Almost surely, 2^1620221663 is an apocalyptic number.

1620221663 is a deficient number, since it is larger than the sum of its proper divisors (328345).

1620221663 is an equidigital number, since it uses as much as digits as its factorization.

1620221663 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 328344.

The product of its (nonzero) digits is 5184, while the sum is 29.

The square root of 1620221663 is about 40251.9771315646. The cubic root of 1620221663 is about 1174.5138566550.

The spelling of 1620221663 in words is "one billion, six hundred twenty million, two hundred twenty-one thousand, six hundred sixty-three".