21122220 has 48 divisors (see below), whose sum is σ = 67592448. Its totient is φ = 4827840.

The previous prime is 21122203. The next prime is 21122221. The reversal of 21122220 is 2222112.

It is a super-2 number, since 2×21122220² = 892296355456800, which 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 = 21122196 and 21122205.

It is not an unprimeable number, because it can be changed into a prime (21122221) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 24726 + ... + 25565.

It is an arithmetic number, because the mean of its divisors is an integer number (1408176).

Almost surely, 2^21122220 is an apocalyptic number.

21122220 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21122220 is an abundant number, since it is smaller than the sum of its proper divisors (46470228).

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

21122220 is a wasteful number, since it uses less digits than its factorization.

21122220 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 50310 (or 50308 counting only the distinct ones).

The product of its (nonzero) digits is 32, while the sum is 12.

The square root of 21122220 is about 4595.8916436313. The cubic root of 21122220 is about 276.4266139240.

Adding to 21122220 its reverse (2222112), we get a palindrome (23344332).

The spelling of 21122220 in words is "twenty-one million, one hundred twenty-two thousand, two hundred twenty".