1663821121 has 4 divisors (see below), whose sum is σ = 1663913044. Its totient is φ = 1663729200.

The previous prime is 1663821101. The next prime is 1663821157. The reversal of 1663821121 is 1211283661.

It is a semiprime because it is the product of two primes, and also a brilliant number, because the two primes have the same length.

It can be written as a sum of positive squares in 2 ways, for example, as 1071580225 + 592240896 = 32735^2 + 24336^2 .

It is a cyclic number.

It is not a de Polignac number, because 1663821121 - 2²⁵ = 1630266689 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (1663821101) 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, 8790 + ... + 58351.

It is an arithmetic number, because the mean of its divisors is an integer number (415978261).

Almost surely, 2^1663821121 is an apocalyptic number.

It is an amenable number.

1663821121 is a deficient number, since it is larger than the sum of its proper divisors (91923).

1663821121 is an equidigital number, since it uses as much as digits as its factorization.

1663821121 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 91922.

The product of its digits is 3456, while the sum is 31.

The square root of 1663821121 is about 40789.9634836806. The cubic root of 1663821121 is about 1184.9559636350.

The spelling of 1663821121 in words is "one billion, six hundred sixty-three million, eight hundred twenty-one thousand, one hundred twenty-one".