21312400205 has 16 divisors (see below), whose sum is σ = 25774619904. Its totient is φ = 16916887680.

The previous prime is 21312400189. The next prime is 21312400247. The reversal of 21312400205 is 50200421312.

It is not a de Polignac number, because 21312400205 - 2⁴ = 21312400189 is a prime.

It is a Duffinian number.

It is a congruent number.

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 15 ways as a sum of consecutive naturals, for example, 1576304 + ... + 1589766.

It is an arithmetic number, because the mean of its divisors is an integer number (1610913744).

Almost surely, 2^21312400205 is an apocalyptic number.

It is an amenable number.

21312400205 is a deficient number, since it is larger than the sum of its proper divisors (4462219699).

21312400205 is a wasteful number, since it uses less digits than its factorization.

21312400205 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 15916.

The product of its (nonzero) digits is 480, while the sum is 20.

Adding to 21312400205 its reverse (50200421312), we get a palindrome (71512821517).

The spelling of 21312400205 in words is "twenty-one billion, three hundred twelve million, four hundred thousand, two hundred five".