21121031204 has 72 divisors (see below), whose sum is σ = 45872507520. Its totient is φ = 8331628032.

The previous prime is 21121031189. The next prime is 21121031231. The reversal of 21121031204 is 40213012112.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 1692572 + ... + 1705004.

It is an arithmetic number, because the mean of its divisors is an integer number (637118160).

Almost surely, 2^21121031204 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21121031204, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (22936253760).

21121031204 is an abundant number, since it is smaller than the sum of its proper divisors (24751476316).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

21121031204 is a wasteful number, since it uses less digits than its factorization.

21121031204 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 12829 (or 12814 counting only the distinct ones).

The product of its (nonzero) digits is 96, while the sum is 17.

Adding to 21121031204 its reverse (40213012112), we get a palindrome (61334043316).

The spelling of 21121031204 in words is "twenty-one billion, one hundred twenty-one million, thirty-one thousand, two hundred four".