21111220020 has 48 divisors (see below), whose sum is σ = 64485183168. Its totient is φ = 5117871360.

The previous prime is 21111220001. The next prime is 21111220037. The reversal of 21111220020 is 2002211112.

It is a super-2 number, since 2×21111220020² (a number of 21 digits) contains 22 as substring.

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 = 21111219978 and 21111220005.

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, 15992689 + ... + 15994008.

It is an arithmetic number, because the mean of its divisors is an integer number (1343441316).

Almost surely, 2^21111220020 is an apocalyptic number.

21111220020 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21111220020 is an abundant number, since it is smaller than the sum of its proper divisors (43373963148).

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

21111220020 is a wasteful number, since it uses less digits than its factorization.

21111220020 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 31986720 (or 31986718 counting only the distinct ones).

The product of its (nonzero) digits is 16, while the sum is 12.

Adding to 21111220020 its reverse (2002211112), we get a palindrome (23113431132).

It can be divided in two parts, 211112 and 20020, that added together give a palindrome (231132).

The spelling of 21111220020 in words is "twenty-one billion, one hundred eleven million, two hundred twenty thousand, twenty".