21042354665 has 8 divisors (see below), whose sum is σ = 25627704000. Its totient is φ = 16582631472.

The previous prime is 21042354649. The next prime is 21042354667. The reversal of 21042354665 is 56645324012.

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

It is a cyclic number.

It is not a de Polignac number, because 21042354665 - 2⁴ = 21042354649 is a prime.

It is not an unprimeable number, because it can be changed into a prime (21042354667) 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 7 ways as a sum of consecutive naturals, for example, 31406165 + ... + 31406834.

It is an arithmetic number, because the mean of its divisors is an integer number (3203463000).

Almost surely, 2^21042354665 is an apocalyptic number.

It is an amenable number.

21042354665 is a deficient number, since it is larger than the sum of its proper divisors (4585349335).

21042354665 is an equidigital number, since it uses as much as digits as its factorization.

21042354665 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 62813071.

The product of its (nonzero) digits is 172800, while the sum is 38.

Adding to 21042354665 its reverse (56645324012), we get a palindrome (77687678677).

The spelling of 21042354665 in words is "twenty-one billion, forty-two million, three hundred fifty-four thousand, six hundred sixty-five".