21555113531 has 8 divisors (see below), whose sum is σ = 24677562624. Its totient is φ = 18443451240.

The previous prime is 21555113479. The next prime is 21555113549. The reversal of 21555113531 is 13531155512.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 21555113531 - 2¹⁰ = 21555112507 is a prime.

It is a super-2 number, since 2×21555113531² (a number of 21 digits) contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21555113431) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 2692415 + ... + 2700408.

It is an arithmetic number, because the mean of its divisors is an integer number (3084695328).

Almost surely, 2^21555113531 is an apocalyptic number.

21555113531 is a deficient number, since it is larger than the sum of its proper divisors (3122449093).

21555113531 is an equidigital number, since it uses as much as digits as its factorization.

21555113531 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 5393401.

The product of its digits is 11250, while the sum is 32.

The spelling of 21555113531 in words is "twenty-one billion, five hundred fifty-five million, one hundred thirteen thousand, five hundred thirty-one".