21101320020 has 48 divisors (see below), whose sum is σ = 64454943168. Its totient is φ = 5115471360.

The previous prime is 21101320007. The next prime is 21101320073. The reversal of 21101320020 is 2002310112.

It is a Harshad number since it is a multiple of its sum of digits (12).

It is a junction number, because it is equal to n+sod(n) for n = 21101319978 and 21101320005.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 15985189 + ... + 15986508.

It is an arithmetic number, because the mean of its divisors is an integer number (1342811316).

Almost surely, 2^21101320020 is an apocalyptic number.

21101320020 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21101320020 is an abundant number, since it is smaller than the sum of its proper divisors (43353623148).

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

21101320020 is a wasteful number, since it uses less digits than its factorization.

21101320020 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 31971720 (or 31971718 counting only the distinct ones).

The product of its (nonzero) digits is 24, while the sum is 12.

Adding to 21101320020 its reverse (2002310112), we get a palindrome (23103630132).

The spelling of 21101320020 in words is "twenty-one billion, one hundred one million, three hundred twenty thousand, twenty".