21681550381345 has 8 divisors (see below), whose sum is σ = 26035079434560. Its totient is φ = 17333760987120.

The previous prime is 21681550381339. The next prime is 21681550381363. The reversal of 21681550381345 is 54318305518612.

It is a happy number.

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

It is not a de Polignac number, because 21681550381345 - 2²⁹ = 21681013510433 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 21681550381292 and 21681550381301.

It is an unprimeable number.

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, 1434906435 + ... + 1434921544.

It is an arithmetic number, because the mean of its divisors is an integer number (3254384929320).

Almost surely, 2^{21681550381345} is an apocalyptic number.

It is an amenable number.

21681550381345 is a deficient number, since it is larger than the sum of its proper divisors (4353529053215).

21681550381345 is a wasteful number, since it uses less digits than its factorization.

21681550381345 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2869829495.

The product of its (nonzero) digits is 3456000, while the sum is 52.

Adding to 21681550381345 its reverse (54318305518612), we get a palindrome (75999855899957).

The spelling of 21681550381345 in words is "twenty-one trillion, six hundred eighty-one billion, five hundred fifty million, three hundred eighty-one thousand, three hundred forty-five".