21155036441545 has 4 divisors (see below), whose sum is σ = 25386043729860. Its totient is φ = 16924029153232.

The previous prime is 21155036441489. The next prime is 21155036441549. The reversal of 21155036441545 is 54514463055112.

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 15448460785209 + 5706575656336 = 3930453^2 + 2388844^2 .

It is a cyclic number.

It is not a de Polignac number, because 21155036441545 - 2²³ = 21155028052937 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 21155036441495 and 21155036441504.

It is not an unprimeable number, because it can be changed into a prime (21155036441549) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 2115503644150 + ... + 2115503644159.

It is an arithmetic number, because the mean of its divisors is an integer number (6346510932465).

Almost surely, 2^{21155036441545} is an apocalyptic number.

It is an amenable number.

21155036441545 is a deficient number, since it is larger than the sum of its proper divisors (4231007288315).

21155036441545 is an equidigital number, since it uses as much as digits as its factorization.

21155036441545 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4231007288314.

The product of its (nonzero) digits is 1440000, while the sum is 46.

Adding to 21155036441545 its reverse (54514463055112), we get a palindrome (75669499496657).

The spelling of 21155036441545 in words is "twenty-one trillion, one hundred fifty-five billion, thirty-six million, four hundred forty-one thousand, five hundred forty-five".