21121202100 has 144 divisors (see below), whose sum is σ = 64787964416. Its totient is φ = 5303232000.

The previous prime is 21121202057. The next prime is 21121202107. The reversal of 21121202100 is 120212112.

It is a super-2 number, since 2×21121202100² (a number of 21 digits) contains 22 as substring.

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

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21121202107) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (23) of ones.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 313410 + ... + 374790.

Almost surely, 2^21121202100 is an apocalyptic number.

21121202100 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 21121202100, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (32393982208).

21121202100 is an abundant number, since it is smaller than the sum of its proper divisors (43666762316).

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

21121202100 is a wasteful number, since it uses less digits than its factorization.

21121202100 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 61466 (or 61459 counting only the distinct ones).

The product of its (nonzero) digits is 16, while the sum is 12.

Adding to 21121202100 its reverse (120212112), we get a palindrome (21241414212).

It can be divided in two parts, 21 and 121202100, that added together give a palindrome (121202121).

The spelling of 21121202100 in words is "twenty-one billion, one hundred twenty-one million, two hundred two thousand, one hundred".