100021220 has 24 divisors (see below), whose sum is σ = 226202424. Its totient is φ = 36930816.

The previous prime is 100021199. The next prime is 100021223. The reversal of 100021220 is 22120001.

It can be written as a sum of positive squares in 4 ways, for example, as 8168164 + 91853056 = 2858^2 + 9584^2 .

It is a junction number, because it is equal to n+sod(n) for n = 100021198 and 100021207.

It is not an unprimeable number, because it can be changed into a prime (100021223) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 192089 + ... + 192608.

It is an arithmetic number, because the mean of its divisors is an integer number (9425101).

Almost surely, 2^100021220 is an apocalyptic number.

100021220 is a gapful number since it is divisible by the number (10) formed by its first and last digit.

It is an amenable number.

100021220 is an abundant number, since it is smaller than the sum of its proper divisors (126181204).

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

100021220 is a wasteful number, since it uses less digits than its factorization.

100021220 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 384719 (or 384717 counting only the distinct ones).

The product of its (nonzero) digits is 8, while the sum is 8.

The square root of 100021220 is about 10001.0609437199. The cubic root of 100021220 is about 464.1917125443.

Adding to 100021220 its reverse (22120001), we get a palindrome (122141221).

The spelling of 100021220 in words is "one hundred million, twenty-one thousand, two hundred twenty".