21253404105 has 40 divisors (see below), whose sum is σ = 38169510984. Its totient is φ = 11314080000.

The previous prime is 21253404091. The next prime is 21253404119. The reversal of 21253404105 is 50140435212.

21253404105 is a `hidden beast` number, since 2 + 1 + 253 + 404 + 1 + 0 + 5 = 666.

It is an interprime number because it is at equal distance from previous prime (21253404091) and next prime (21253404119).

It can be written as a sum of positive squares in 4 ways, for example, as 3268180224 + 17985223881 = 57168^2 + 134109^2 .

It is not a de Polignac number, because 21253404105 - 2⁸ = 21253403849 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (27).

It is an unprimeable number.

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 39 ways as a sum of consecutive naturals, for example, 170605 + ... + 267605.

Almost surely, 2^21253404105 is an apocalyptic number.

It is an amenable number.

21253404105 is a deficient number, since it is larger than the sum of its proper divisors (16916106879).

21253404105 is an equidigital number, since it uses as much as digits as its factorization.

21253404105 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 97559 (or 97550 counting only the distinct ones).

The product of its (nonzero) digits is 4800, while the sum is 27.

Adding to 21253404105 its reverse (50140435212), we get a palindrome (71393839317).

The spelling of 21253404105 in words is "twenty-one billion, two hundred fifty-three million, four hundred four thousand, one hundred five".