21531503404553 has 4 divisors (see below), whose sum is σ = 21804054080640. Its totient is φ = 21258952728468.

The previous prime is 21531503404519. The next prime is 21531503404561. The reversal of 21531503404553 is 35540430513512.

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 not a de Polignac number, because 21531503404553 - 2²⁰ = 21531502355977 is a prime.

It is a super-2 number, since 2×21531503404553² (a number of 27 digits) contains 22 as substring.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 21531503404553.

It is not an unprimeable number, because it can be changed into a prime (21531503401553) 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, 136275337925 + ... + 136275338082.

It is an arithmetic number, because the mean of its divisors is an integer number (5451013520160).

Almost surely, 2^{21531503404553} is an apocalyptic number.

It is an amenable number.

21531503404553 is a deficient number, since it is larger than the sum of its proper divisors (272550676087).

21531503404553 is an equidigital number, since it uses as much as digits as its factorization.

21531503404553 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 272550676086.

The product of its (nonzero) digits is 540000, while the sum is 41.

The spelling of 21531503404553 in words is "twenty-one trillion, five hundred thirty-one billion, five hundred three million, four hundred four thousand, five hundred fifty-three".