21001100022 has 72 divisors (see below), whose sum is σ = 53119011816. Its totient is φ = 5979040704.

The previous prime is 21001100017. The next prime is 21001100023. The reversal of 21001100022 is 22000110012.

It is a Harshad number since it is a multiple of its sum of digits (9).

It is a junction number, because it is equal to n+sod(n) for n = 21001099977 and 21001100013.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21001100023) by changing a digit.

It is a polite number, since it can be written in 35 ways as a sum of consecutive naturals, for example, 207538 + ... + 291674.

It is an arithmetic number, because the mean of its divisors is an integer number (737764053).

Almost surely, 2^21001100022 is an apocalyptic number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21001100022, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (26559505908).

21001100022 is an abundant number, since it is smaller than the sum of its proper divisors (32117911794).

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

21001100022 is a wasteful number, since it uses less digits than its factorization.

21001100022 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 84442 (or 84432 counting only the distinct ones).

The product of its (nonzero) digits is 8, while the sum is 9.

Adding to 21001100022 its reverse (22000110012), we get a palindrome (43001210034).

The spelling of 21001100022 in words is "twenty-one billion, one million, one hundred thousand, twenty-two".