21002122100 has 36 divisors (see below), whose sum is σ = 46086698700. Its totient is φ = 8306453760.

The previous prime is 21002122091. The next prime is 21002122109. The reversal of 21002122100 is 122120012.

It is a happy number.

It is an interprime number because it is at equal distance from previous prime (21002122091) and next prime (21002122109).

It can be written as a sum of positive squares in 6 ways, for example, as 3375842404 + 17626279696 = 58102^2 + 132764^2 .

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21002122109) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 1170995 + ... + 1188794.

It is an arithmetic number, because the mean of its divisors is an integer number (1280186075).

Almost surely, 2^21002122100 is an apocalyptic number.

21002122100 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21002122100 is an abundant number, since it is smaller than the sum of its proper divisors (25084576600).

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

21002122100 is a wasteful number, since it uses less digits than its factorization.

21002122100 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2359892 (or 2359885 counting only the distinct ones).

The product of its (nonzero) digits is 16, while the sum is 11.

Adding to 21002122100 its reverse (122120012), we get a palindrome (21124242112).

The spelling of 21002122100 in words is "twenty-one billion, two million, one hundred twenty-two thousand, one hundred".