21612126553 has 4 divisors (see below), whose sum is σ = 21613212160. Its totient is φ = 21611040948.

The previous prime is 21612126533. The next prime is 21612126559. The reversal of 21612126553 is 35562121612.

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-21612126553 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21612126559) 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, 512373 + ... + 552946.

It is an arithmetic number, because the mean of its divisors is an integer number (5403303040).

Almost surely, 2^21612126553 is an apocalyptic number.

It is an amenable number.

21612126553 is a deficient number, since it is larger than the sum of its proper divisors (1085607).

21612126553 is a wasteful number, since it uses less digits than its factorization.

21612126553 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1085606.

The product of its digits is 21600, while the sum is 34.

The spelling of 21612126553 in words is "twenty-one billion, six hundred twelve million, one hundred twenty-six thousand, five hundred fifty-three".