21521344153 has 4 divisors (see below), whose sum is σ = 22046255028. Its totient is φ = 20996433280.

The previous prime is 21521344139. The next prime is 21521344171. The reversal of 21521344153 is 35144312512.

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 360696064 + 21160648089 = 18992^2 + 145467^2 .

It is a cyclic number.

It is not a de Polignac number, because 21521344153 - 2⁵ = 21521344121 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21521344253) 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, 262455376 + ... + 262455457.

It is an arithmetic number, because the mean of its divisors is an integer number (5511563757).

Almost surely, 2^21521344153 is an apocalyptic number.

It is an amenable number.

21521344153 is a deficient number, since it is larger than the sum of its proper divisors (524910875).

21521344153 is an equidigital number, since it uses as much as digits as its factorization.

21521344153 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 524910874.

The product of its digits is 14400, while the sum is 31.

Adding to 21521344153 its reverse (35144312512), we get a palindrome (56665656665).

The spelling of 21521344153 in words is "twenty-one billion, five hundred twenty-one million, three hundred forty-four thousand, one hundred fifty-three".