21000822 has 16 divisors (see below), whose sum is σ = 42895872. Its totient is φ = 6851240.

The previous prime is 21000821. The next prime is 21000823. The reversal of 21000822 is 22800012.

It is an interprime number because it is at equal distance from previous prime (21000821) and next prime (21000823).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21000821) 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 7 ways as a sum of consecutive naturals, for example, 36954 + ... + 37517.

It is an arithmetic number, because the mean of its divisors is an integer number (2680992).

Almost surely, 2^21000822 is an apocalyptic number.

21000822 is an abundant number, since it is smaller than the sum of its proper divisors (21895050).

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

21000822 is a wasteful number, since it uses less digits than its factorization.

21000822 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 74523.

The product of its (nonzero) digits is 64, while the sum is 15.

The square root of 21000822 is about 4582.6653816311. The cubic root of 21000822 is about 275.8960173303.

Adding to 21000822 its reverse (22800012), we get a palindrome (43800834).

The spelling of 21000822 in words is "twenty-one million, eight hundred twenty-two", and thus it is an aban number.