21544142545 has 4 divisors (see below), whose sum is σ = 25852971060. Its totient is φ = 17235314032.

The previous prime is 21544142539. The next prime is 21544142549. The reversal of 21544142545 is 54524144512.

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 13857762961 + 7686379584 = 117719^2 + 87672^2 .

It is a cyclic number.

It is not a de Polignac number, because 21544142545 - 2³ = 21544142537 is a prime.

It is not an unprimeable number, because it can be changed into a prime (21544142549) 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, 2154414250 + ... + 2154414259.

It is an arithmetic number, because the mean of its divisors is an integer number (6463242765).

Almost surely, 2^21544142545 is an apocalyptic number.

It is an amenable number.

21544142545 is a deficient number, since it is larger than the sum of its proper divisors (4308828515).

21544142545 is an equidigital number, since it uses as much as digits as its factorization.

21544142545 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4308828514.

The product of its digits is 128000, while the sum is 37.

The spelling of 21544142545 in words is "twenty-one billion, five hundred forty-four million, one hundred forty-two thousand, five hundred forty-five".