21101911020 has 168 divisors, whose sum is σ = 66607035264. Its totient is φ = 5613090048.

The previous prime is 21101910997. The next prime is 21101911063. The reversal of 21101911020 is 2011910112.

It is a happy number.

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 = 21101910984 and 21101911002.

It is an unprimeable number.

It is a polite number, since it can be written in 55 ways as a sum of consecutive naturals, for example, 6661477 + ... + 6664643.

It is an arithmetic number, because the mean of its divisors is an integer number (396470448).

Almost surely, 2^21101911020 is an apocalyptic number.

21101911020 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21101911020, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (33303517632).

21101911020 is an abundant number, since it is smaller than the sum of its proper divisors (45505124244).

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

21101911020 is a wasteful number, since it uses less digits than its factorization.

21101911020 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3651 (or 3634 counting only the distinct ones).

The product of its (nonzero) digits is 36, while the sum is 18.

The spelling of 21101911020 in words is "twenty-one billion, one hundred one million, nine hundred eleven thousand, twenty".