21533343555121 has 4 divisors (see below), whose sum is σ = 21534254965872. Its totient is φ = 21532432144372.

The previous prime is 21533343555107. The next prime is 21533343555149. The reversal of 21533343555121 is 12155534333512.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21533343555121 is a prime.

It is a super-2 number, since 2×21533343555121² (a number of 27 digits) contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21533343555221) 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, 455669935 + ... + 455717188.

It is an arithmetic number, because the mean of its divisors is an integer number (5383563741468).

Almost surely, 2^{21533343555121} is an apocalyptic number.

It is an amenable number.

21533343555121 is a deficient number, since it is larger than the sum of its proper divisors (911410751).

21533343555121 is an equidigital number, since it uses as much as digits as its factorization.

21533343555121 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 911410750.

The product of its digits is 810000, while the sum is 43.

Adding to 21533343555121 its reverse (12155534333512), we get a palindrome (33688877888633).

The spelling of 21533343555121 in words is "twenty-one trillion, five hundred thirty-three billion, three hundred forty-three million, five hundred fifty-five thousand, one hundred twenty-one".