21162820 has 24 divisors (see below), whose sum is σ = 50791104. Its totient is φ = 7255776.

The previous prime is 21162811. The next prime is 21162839. The reversal of 21162820 is 2826112.

It is a super-3 number, since 3×21162820³ (a number of 23 digits) contains 333 as substring.

It is a junction number, because it is equal to n+sod(n) for n = 21162791 and 21162800.

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 7 ways as a sum of consecutive naturals, for example, 75442 + ... + 75721.

It is an arithmetic number, because the mean of its divisors is an integer number (2116296).

Almost surely, 2^21162820 is an apocalyptic number.

21162820 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21162820 is an abundant number, since it is smaller than the sum of its proper divisors (29628284).

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

21162820 is a wasteful number, since it uses less digits than its factorization.

21162820 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 151179 (or 151177 counting only the distinct ones).

The product of its (nonzero) digits is 384, while the sum is 22.

The square root of 21162820 is about 4600.3065115272. The cubic root of 21162820 is about 276.6036113781.

Adding to 21162820 its reverse (2826112), we get a palindrome (23988932).

The spelling of 21162820 in words is "twenty-one million, one hundred sixty-two thousand, eight hundred twenty".