21102420204020 has 24 divisors (see below), whose sum is σ = 45041559192168. Its totient is φ = 8302591555200.

The previous prime is 21102420204013. The next prime is 21102420204023. The reversal of 21102420204020 is 2040202420112.

It can be written as a sum of positive squares in 4 ways, for example, as 1100577239056 + 20001842964964 = 1049084^2 + 4472342^2 .

It is a Harshad number since it is a multiple of its sum of digits (20).

It is a junction number, because it is equal to n+sod(n) for n = 21102420203983 and 21102420204001.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21102420204023) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 8648531651 + ... + 8648534090.

It is an arithmetic number, because the mean of its divisors is an integer number (1876731633007).

Almost surely, 2^{21102420204020} is an apocalyptic number.

21102420204020 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21102420204020 is an abundant number, since it is smaller than the sum of its proper divisors (23939138988148).

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

21102420204020 is a wasteful number, since it uses less digits than its factorization.

21102420204020 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 17297065811 (or 17297065809 counting only the distinct ones).

The product of its (nonzero) digits is 512, while the sum is 20.

Adding to 21102420204020 its reverse (2040202420112), we get a palindrome (23142622624132).

The spelling of 21102420204020 in words is "twenty-one trillion, one hundred two billion, four hundred twenty million, two hundred four thousand, twenty".