21154023545 has 8 divisors (see below), whose sum is σ = 25388910024. Its totient is φ = 16920497664.

The previous prime is 21154023511. The next prime is 21154023557. The reversal of 21154023545 is 54532045112.

It can be written as a sum of positive squares in 4 ways, for example, as 10547495401 + 10606528144 = 102701^2 + 102988^2 .

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 21154023545 - 2⁶ = 21154023481 is a prime.

It is a Duffinian number.

It is a Curzon number.

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, 305624 + ... + 368393.

It is an arithmetic number, because the mean of its divisors is an integer number (3173613753).

Almost surely, 2^21154023545 is an apocalyptic number.

It is an amenable number.

21154023545 is a deficient number, since it is larger than the sum of its proper divisors (4234886479).

21154023545 is an equidigital number, since it uses as much as digits as its factorization.

21154023545 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 680299.

The product of its (nonzero) digits is 24000, while the sum is 32.

Adding to 21154023545 its reverse (54532045112), we get a palindrome (75686068657).

The spelling of 21154023545 in words is "twenty-one billion, one hundred fifty-four million, twenty-three thousand, five hundred forty-five".