21101220100 has 18 divisors (see below), whose sum is σ = 45789647834. Its totient is φ = 8440488000.

The previous prime is 21101220083. The next prime is 21101220103. The reversal of 21101220100 is 102210112.

It can be written as a sum of positive squares in 3 ways, for example, as 4670082244 + 16431137856 = 68338^2 + 128184^2 .

It is a super-2 number, since 2×21101220100² (a number of 21 digits) contains 22 as substring.

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

It is not an unprimeable number, because it can be changed into a prime (21101220103) by changing a digit.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 105506001 + ... + 105506200.

Almost surely, 2^21101220100 is an apocalyptic number.

21101220100 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21101220100 is an abundant number, since it is smaller than the sum of its proper divisors (24688427734).

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

21101220100 is a wasteful number, since it uses less digits than its factorization.

21101220100 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 211012215 (or 211012208 counting only the distinct ones).

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

Adding to 21101220100 its reverse (102210112), we get a palindrome (21203430212).

The spelling of 21101220100 in words is "twenty-one billion, one hundred one million, two hundred twenty thousand, one hundred".