21206322 has 48 divisors (see below), whose sum is σ = 48379968. Its totient is φ = 6700320.

The previous prime is 21206303. The next prime is 21206323. The reversal of 21206322 is 22360212.

It is a Harshad number since it is a multiple of its sum of digits (18).

It is a junction number, because it is equal to n+sod(n) for n = 21206295 and 21206304.

It is not an unprimeable number, because it can be changed into a prime (21206323) 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 23 ways as a sum of consecutive naturals, for example, 74793 + ... + 75075.

It is an arithmetic number, because the mean of its divisors is an integer number (1007916).

Almost surely, 2^21206322 is an apocalyptic number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21206322, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (24189984).

21206322 is an abundant number, since it is smaller than the sum of its proper divisors (27173646).

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

21206322 is a wasteful number, since it uses less digits than its factorization.

21206322 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 495 (or 492 counting only the distinct ones).

The product of its (nonzero) digits is 288, while the sum is 18.

The square root of 21206322 is about 4605.0322474441. The cubic root of 21206322 is about 276.7930091817.

Adding to 21206322 its reverse (22360212), we get a palindrome (43566534).

It can be divided in two parts, 21206 and 322, that added together give a triangular number (21528 = T₂₀₇).

The spelling of 21206322 in words is "twenty-one million, two hundred six thousand, three hundred twenty-two".