21100444020 has 72 divisors (see below), whose sum is σ = 64020378240. Its totient is φ = 5625405120.

The previous prime is 21100444019. The next prime is 21100444021. The reversal of 21100444020 is 2044400112.

It is an interprime number because it is at equal distance from previous prime (21100444019) and next prime (21100444021).

It is a Harshad number since it is a multiple of its sum of digits (18).

It is a junction number, because it is equal to n+sod(n) for n = 21100443984 and 21100444002.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21100444021) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 873505 + ... + 897335.

It is an arithmetic number, because the mean of its divisors is an integer number (889171920).

Almost surely, 2^21100444020 is an apocalyptic number.

21100444020 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21100444020 is an abundant number, since it is smaller than the sum of its proper divisors (42919934220).

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

21100444020 is a wasteful number, since it uses less digits than its factorization.

21100444020 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 28765 (or 28760 counting only the distinct ones).

The product of its (nonzero) digits is 256, while the sum is 18.

Adding to 21100444020 its reverse (2044400112), we get a palindrome (23144844132).

The spelling of 21100444020 in words is "twenty-one billion, one hundred million, four hundred forty-four thousand, twenty".