21312020100 has 288 divisors, whose sum is σ = 72032889600. Its totient is φ = 4764672000.

The previous prime is 21312020099. The next prime is 21312020101. The reversal of 21312020100 is 102021312.

It is an interprime number because it is at equal distance from previous prime (21312020099) and next prime (21312020101).

It is a Harshad number since it is a multiple of its sum of digits (12).

It is not an unprimeable number, because it can be changed into a prime (21312020101) by changing a digit.

It is a polite number, since it can be written in 95 ways as a sum of consecutive naturals, for example, 18876336 + ... + 18877464.

It is an arithmetic number, because the mean of its divisors is an integer number (250114200).

Almost surely, 2^21312020100 is an apocalyptic number.

21312020100 is a gapful number since it is divisible by the number (20) 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 21312020100, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (36016444800).

21312020100 is an abundant number, since it is smaller than the sum of its proper divisors (50720869500).

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

21312020100 is a wasteful number, since it uses less digits than its factorization.

21312020100 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1343 (or 1336 counting only the distinct ones).

The product of its (nonzero) digits is 24, while the sum is 12.

Adding to 21312020100 its reverse (102021312), we get a palindrome (21414041412).

The spelling of 21312020100 in words is "twenty-one billion, three hundred twelve million, twenty thousand, one hundred".