21161003641 has 4 divisors (see below), whose sum is σ = 21170045284. Its totient is φ = 21151962000.

The previous prime is 21161003573. The next prime is 21161003653. The reversal of 21161003641 is 14630016112.

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

It can be written as a sum of positive squares in 2 ways, for example, as 6149853241 + 15011150400 = 78421^2 + 122520^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21161003641 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21161003671) 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, 4517310 + ... + 4521991.

It is an arithmetic number, because the mean of its divisors is an integer number (5292511321).

Almost surely, 2^21161003641 is an apocalyptic number.

It is an amenable number.

21161003641 is a deficient number, since it is larger than the sum of its proper divisors (9041643).

21161003641 is an equidigital number, since it uses as much as digits as its factorization.

21161003641 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 9041642.

The product of its (nonzero) digits is 864, while the sum is 25.

Adding to 21161003641 its reverse (14630016112), we get a palindrome (35791019753).

The spelling of 21161003641 in words is "twenty-one billion, one hundred sixty-one million, three thousand, six hundred forty-one".