21212040404 has 12 divisors (see below), whose sum is σ = 37309503924. Its totient is φ = 10552182144.

The previous prime is 21212040391. The next prime is 21212040427. The reversal of 21212040404 is 40404021212.

It can be written as a sum of positive squares in 2 ways, for example, as 11946052804 + 9265987600 = 109298^2 + 96260^2 .

21212040404 is a modest number, since divided by 40404 gives 21212 as remainder.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 13458629 + ... + 13460204.

It is an arithmetic number, because the mean of its divisors is an integer number (3109125327).

Almost surely, 2^21212040404 is an apocalyptic number.

It is an amenable number.

21212040404 is a deficient number, since it is larger than the sum of its proper divisors (16097463520).

21212040404 is a wasteful number, since it uses less digits than its factorization.

21212040404 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 26919034 (or 26919032 counting only the distinct ones).

The product of its (nonzero) digits is 512, while the sum is 20.

Adding to 21212040404 its reverse (40404021212), we get a palindrome (61616061616).

The spelling of 21212040404 in words is "twenty-one billion, two hundred twelve million, forty thousand, four hundred four".