101821220 has 12 divisors (see below), whose sum is σ = 213824604. Its totient is φ = 40728480.

The previous prime is 101821219. The next prime is 101821229. The reversal of 101821220 is 22128101.

It is a happy number.

It can be written as a sum of positive squares in 2 ways, for example, as 75030244 + 26790976 = 8662^2 + 5176^2 .

It is not an unprimeable number, because it can be changed into a prime (101821229) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 2545511 + ... + 2545550.

It is an arithmetic number, because the mean of its divisors is an integer number (17818717).

Almost surely, 2^101821220 is an apocalyptic number.

101821220 is a gapful number since it is divisible by the number (10) formed by its first and last digit.

It is an amenable number.

101821220 is an abundant number, since it is smaller than the sum of its proper divisors (112003384).

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

101821220 is a wasteful number, since it uses less digits than its factorization.

101821220 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 5091070 (or 5091068 counting only the distinct ones).

The product of its (nonzero) digits is 64, while the sum is 17.

The square root of 101821220 is about 10090.6501277172. The cubic root of 101821220 is about 466.9597331494.

Adding to 101821220 its reverse (22128101), we get a palindrome (123949321).

The spelling of 101821220 in words is "one hundred one million, eight hundred twenty-one thousand, two hundred twenty".