21540252245 has 4 divisors (see below), whose sum is σ = 25848302700. Its totient is φ = 17232201792.

The previous prime is 21540252241. The next prime is 21540252247. The reversal of 21540252245 is 54225204512.

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 7046259364 + 14493992881 = 83942^2 + 120391^2 .

It is a cyclic number.

It is not a de Polignac number, because 21540252245 - 2² = 21540252241 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21540252241) 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, 2154025220 + ... + 2154025229.

It is an arithmetic number, because the mean of its divisors is an integer number (6462075675).

Almost surely, 2^21540252245 is an apocalyptic number.

It is an amenable number.

21540252245 is a deficient number, since it is larger than the sum of its proper divisors (4308050455).

21540252245 is an equidigital number, since it uses as much as digits as its factorization.

21540252245 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4308050454.

The product of its (nonzero) digits is 32000, while the sum is 32.

Adding to 21540252245 its reverse (54225204512), we get a palindrome (75765456757).

The spelling of 21540252245 in words is "twenty-one billion, five hundred forty million, two hundred fifty-two thousand, two hundred forty-five".