21011223220 has 48 divisors (see below), whose sum is σ = 47530119168. Its totient is φ = 7755960960.

The previous prime is 21011223217. The next prime is 21011223271. The reversal of 21011223220 is 2232211012.

It is a happy number.

It is a junction number, because it is equal to n+sod(n) for n = 21011223194 and 21011223203.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 1294797 + ... + 1310923.

It is an arithmetic number, because the mean of its divisors is an integer number (990210816).

Almost surely, 2^21011223220 is an apocalyptic number.

21011223220 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21011223220 is an abundant number, since it is smaller than the sum of its proper divisors (26518895948).

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

21011223220 is a wasteful number, since it uses less digits than its factorization.

21011223220 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 21160 (or 21158 counting only the distinct ones).

The product of its (nonzero) digits is 96, while the sum is 16.

Adding to 21011223220 its reverse (2232211012), we get a palindrome (23243434232).

It can be divided in two parts, 210112 and 23220, that added together give a palindrome (233332).

The spelling of 21011223220 in words is "twenty-one billion, eleven million, two hundred twenty-three thousand, two hundred twenty".