21660531255 has 144 divisors (see below), whose sum is σ = 42855740928. Its totient is φ = 10105603200.

The previous prime is 21660531251. The next prime is 21660531271. The reversal of 21660531255 is 55213506612.

21660531255 is a `hidden beast` number, since 2 + 16 + 60 + 531 + 2 + 55 = 666.

It is not a de Polignac number, because 21660531255 - 2² = 21660531251 is a prime.

It is a super-2 number, since 2×21660531255² (a number of 21 digits) contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21660531251) 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 143 ways as a sum of consecutive naturals, for example, 16622934 + ... + 16624236.

It is an arithmetic number, because the mean of its divisors is an integer number (297609312).

Almost surely, 2^21660531255 is an apocalyptic number.

21660531255 is a deficient number, since it is larger than the sum of its proper divisors (21195209673).

21660531255 is a wasteful number, since it uses less digits than its factorization.

21660531255 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1450 (or 1436 counting only the distinct ones).

The product of its (nonzero) digits is 54000, while the sum is 36.

The spelling of 21660531255 in words is "twenty-one billion, six hundred sixty million, five hundred thirty-one thousand, two hundred fifty-five".