21311212104 has 480 divisors, whose sum is σ = 79202665080. Its totient is φ = 5288177664.

The previous prime is 21311212099. The next prime is 21311212127. The reversal of 21311212104 is 40121211312.

It can be written as a sum of positive squares in 4 ways, for example, as 20021684004 + 1289528100 = 141498^2 + 35910^2 .

It is a super-3 number, since 3×21311212104³ (a number of 32 digits) contains 333 as substring. Note that it is a super-d number also for d = 2.

It is a Harshad number since it is a multiple of its sum of digits (18).

It is an unprimeable number.

It is a polite number, since it can be written in 119 ways as a sum of consecutive naturals, for example, 7015674 + ... + 7018710.

Almost surely, 2^21311212104 is an apocalyptic number.

21311212104 is a gapful number since it is divisible by the number (24) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21311212104, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (39601332540).

21311212104 is an abundant number, since it is smaller than the sum of its proper divisors (57891452976).

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

21311212104 is a wasteful number, since it uses less digits than its factorization.

21311212104 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3099 (or 3079 counting only the distinct ones).

The product of its (nonzero) digits is 96, while the sum is 18.

Adding to 21311212104 its reverse (40121211312), we get a palindrome (61432423416).

The spelling of 21311212104 in words is "twenty-one billion, three hundred eleven million, two hundred twelve thousand, one hundred four".