21122123220 has 96 divisors (see below), whose sum is σ = 71687226240. Its totient is φ = 5120513280.

The previous prime is 21122123213. The next prime is 21122123221. The reversal of 21122123220 is 2232122112.

21122123220 is a `hidden beast` number, since 211 + 221 + 232 + 2 + 0 = 666.

It is a super-2 number, since 2×21122123220² (a number of 21 digits) contains 22 as substring.

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 = 21122123193 and 21122123202.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21122123221) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 1772017 + ... + 1783896.

It is an arithmetic number, because the mean of its divisors is an integer number (746741940).

Almost surely, 2^21122123220 is an apocalyptic number.

21122123220 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21122123220 is an abundant number, since it is smaller than the sum of its proper divisors (50565103020).

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

21122123220 is a wasteful number, since it uses less digits than its factorization.

21122123220 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3555942 (or 3555934 counting only the distinct ones).

The product of its (nonzero) digits is 192, while the sum is 18.

Adding to 21122123220 its reverse (2232122112), we get a palindrome (23354245332).

The spelling of 21122123220 in words is "twenty-one billion, one hundred twenty-two million, one hundred twenty-three thousand, two hundred twenty".