21100320 has 72 divisors (see below), whose sum is σ = 72009756. Its totient is φ = 5626368.

The previous prime is 21100319. The next prime is 21100351. The reversal of 21100320 is 2300112.

It is a happy number.

It can be written as a sum of positive squares in 2 ways, for example, as 20903184 + 197136 = 4572^2 + 444^2 .

It is a tau number, because it is divible by the number of its divisors (72).

It is a Harshad number since it is a multiple of its sum of digits (9).

It is an unprimeable number.

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 11 ways as a sum of consecutive naturals, for example, 5887 + ... + 8766.

Almost surely, 2^21100320 is an apocalyptic number.

21100320 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21100320 is an abundant number, since it is smaller than the sum of its proper divisors (50909436).

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

21100320 is a wasteful number, since it uses less digits than its factorization.

21100320 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 14674 (or 14663 counting only the distinct ones).

The product of its (nonzero) digits is 12, while the sum is 9.

The square root of 21100320 is about 4593.5084630378. The cubic root of 21100320 is about 276.3310457455.

Adding to 21100320 its reverse (2300112), we get a palindrome (23400432).

The spelling of 21100320 in words is "twenty-one million, one hundred thousand, three hundred twenty".