21820000 has 60 divisors (see below), whose sum is σ = 53729676. Its totient is φ = 8720000.

The previous prime is 21819991. The next prime is 21820013. The reversal of 21820000 is 2812.

It is a super-2 number, since 2×21820000² = 952224800000000, which contains 22 as substring.

It is a congruent number.

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 9 ways as a sum of consecutive naturals, for example, 19455 + ... + 20545.

Almost surely, 2^21820000 is an apocalyptic number.

21820000 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21820000, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (26864838).

21820000 is an abundant number, since it is smaller than the sum of its proper divisors (31909676).

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

21820000 is an equidigital number, since it uses as much as digits as its factorization.

21820000 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1121 (or 1098 counting only the distinct ones).

The product of its (nonzero) digits is 32, while the sum is 13.

The square root of 21820000 is about 4671.1882856507. The cubic root of 21820000 is about 279.4376468339.

Adding to 21820000 its reverse (2812), we get a palindrome (21822812).

The spelling of 21820000 in words is "twenty-one million, eight hundred twenty thousand".