21161003665 has 8 divisors (see below), whose sum is σ = 26729688960. Its totient is φ = 16037813232.

The previous prime is 21161003653. The next prime is 21161003671. The reversal of 21161003665 is 56630016112.

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-21161003665 is a prime.

It is a super-2 number, since 2×21161003665² (a number of 21 digits) contains 22 as substring.

It is an unprimeable number.

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 7 ways as a sum of consecutive naturals, for example, 111373609 + ... + 111373798.

It is an arithmetic number, because the mean of its divisors is an integer number (3341211120).

Almost surely, 2^21161003665 is an apocalyptic number.

It is an amenable number.

21161003665 is a deficient number, since it is larger than the sum of its proper divisors (5568685295).

21161003665 is a wasteful number, since it uses less digits than its factorization.

21161003665 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 222747431.

The product of its (nonzero) digits is 6480, while the sum is 31.

Adding to 21161003665 its reverse (56630016112), we get a palindrome (77791019777).

The spelling of 21161003665 in words is "twenty-one billion, one hundred sixty-one million, three thousand, six hundred sixty-five".