21240204105 has 32 divisors (see below), whose sum is σ = 36286626816. Its totient is φ = 10583584704.

The previous prime is 21240204079. The next prime is 21240204149. The reversal of 21240204105 is 50140204212.

It is not a de Polignac number, because 21240204105 - 2¹⁰ = 21240203081 is a prime.

It is a super-2 number, since 2×21240204105² (a number of 21 digits) contains 22 as substring.

It is a Curzon number.

It is an unprimeable number.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 701047 + ... + 730716.

It is an arithmetic number, because the mean of its divisors is an integer number (1133957088).

Almost surely, 2^21240204105 is an apocalyptic number.

It is an amenable number.

21240204105 is a deficient number, since it is larger than the sum of its proper divisors (15046422711).

21240204105 is a wasteful number, since it uses less digits than its factorization.

21240204105 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1431837.

The product of its (nonzero) digits is 640, while the sum is 21.

Adding to 21240204105 its reverse (50140204212), we get a palindrome (71380408317).

The spelling of 21240204105 in words is "twenty-one billion, two hundred forty million, two hundred four thousand, one hundred five".