21112671205 has 16 divisors (see below), whose sum is σ = 26241375600. Its totient is φ = 16287470080.

The previous prime is 21112671197. The next prime is 21112671233. The reversal of 21112671205 is 50217621112.

It is a Cunningham number, because it is equal to 145302²+1.

It can be written as a sum of positive squares in 8 ways, for example, as 1727399844 + 19385271361 = 41562^2 + 139231^2 .

It is not a de Polignac number, because 21112671205 - 2³ = 21112671197 is a prime.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 27315 + ... + 207295.

It is an arithmetic number, because the mean of its divisors is an integer number (1640085975).

Almost surely, 2^21112671205 is an apocalyptic number.

It is an amenable number.

21112671205 is a deficient number, since it is larger than the sum of its proper divisors (5128704395).

21112671205 is a wasteful number, since it uses less digits than its factorization.

21112671205 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 180824.

The product of its (nonzero) digits is 1680, while the sum is 28.

The spelling of 21112671205 in words is "twenty-one billion, one hundred twelve million, six hundred seventy-one thousand, two hundred five".