21311321100 has 36 divisors (see below), whose sum is σ = 61660756584. Its totient is φ = 5683018880.

The previous prime is 21311321099. The next prime is 21311321137. The reversal of 21311321100 is 112311312.

It is a happy number.

It is a Harshad number since it is a multiple of its sum of digits (15).

It is a self number, because there is not a number n which added to its sum of digits gives 21311321100.

It is an unprimeable number.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 35518569 + ... + 35519168.

It is an arithmetic number, because the mean of its divisors is an integer number (1712798794).

Almost surely, 2^21311321100 is an apocalyptic number.

21311321100 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21311321100 is an abundant number, since it is smaller than the sum of its proper divisors (40349435484).

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

21311321100 is a wasteful number, since it uses less digits than its factorization.

21311321100 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 71037754 (or 71037747 counting only the distinct ones).

The product of its (nonzero) digits is 36, while the sum is 15.

Adding to 21311321100 its reverse (112311312), we get a palindrome (21423632412).

It can be divided in two parts, 2131 and 1321100, that added together give a palindrome (1323231).

The spelling of 21311321100 in words is "twenty-one billion, three hundred eleven million, three hundred twenty-one thousand, one hundred".