21212100100 has 36 divisors (see below), whose sum is σ = 46437629364. Its totient is φ = 8409748480.

The previous prime is 21212100097. The next prime is 21212100121. The reversal of 21212100100 is 100121212.

It can be written as a sum of positive squares in 6 ways, for example, as 3981862404 + 17230237696 = 63102^2 + 131264^2 .

It is a super-3 number, since 3×21212100100³ (a number of 32 digits) contains 333 as substring.

It is a Harshad number since it is a multiple of its sum of digits (10).

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, 927289 + ... + 949888.

It is an arithmetic number, because the mean of its divisors is an integer number (1289934149).

Almost surely, 2^21212100100 is an apocalyptic number.

21212100100 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21212100100 is an abundant number, since it is smaller than the sum of its proper divisors (25225529264).

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

21212100100 is a wasteful number, since it uses less digits than its factorization.

21212100100 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1877304 (or 1877297 counting only the distinct ones).

The product of its (nonzero) digits is 8, while the sum is 10.

Adding to 21212100100 its reverse (100121212), we get a palindrome (21312221312).

The spelling of 21212100100 in words is "twenty-one billion, two hundred twelve million, one hundred thousand, one hundred".