21385255545 has 96 divisors (see below), whose sum is σ = 38996100000. Its totient is φ = 10827177984.

The previous prime is 21385255469. The next prime is 21385255547. The reversal of 21385255545 is 54555258312.

21385255545 is a `hidden beast` number, since 2 + 1 + 3 + 8 + 52 + 55 + 545 = 666.

It can be written as a sum of positive squares in 16 ways, for example, as 8191517049 + 13193738496 = 90507^2 + 114864^2 .

It is not a de Polignac number, because 21385255545 - 2⁸ = 21385255289 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (45).

It is a self number, because there is not a number n which added to its sum of digits gives 21385255545.

It is not an unprimeable number, because it can be changed into a prime (21385255547) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 95 ways as a sum of consecutive naturals, for example, 21194001 + ... + 21195009.

It is an arithmetic number, because the mean of its divisors is an integer number (406209375).

Almost surely, 2^21385255545 is an apocalyptic number.

It is an amenable number.

21385255545 is a deficient number, since it is larger than the sum of its proper divisors (17610844455).

21385255545 is a wasteful number, since it uses less digits than its factorization.

21385255545 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1307 (or 1304 counting only the distinct ones).

The product of its digits is 1200000, while the sum is 45.

The spelling of 21385255545 in words is "twenty-one billion, three hundred eighty-five million, two hundred fifty-five thousand, five hundred forty-five".