21222786 has 64 divisors (see below), whose sum is σ = 48254976. Its totient is φ = 6177600.

The previous prime is 21222757. The next prime is 21222787. The reversal of 21222786 is 68722212.

It is not an unprimeable number, because it can be changed into a prime (21222787) 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 31 ways as a sum of consecutive naturals, for example, 161941 + ... + 162071.

It is an arithmetic number, because the mean of its divisors is an integer number (753984).

Almost surely, 2^21222786 is an apocalyptic number.

21222786 is a gapful number since it is divisible by the number (26) formed by its first and last digit.

It is a practical number, because each smaller number is the sum of distinct divisors of 21222786, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (24127488).

21222786 is an abundant number, since it is smaller than the sum of its proper divisors (27032190).

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

21222786 is a wasteful number, since it uses less digits than its factorization.

21222786 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 247.

The product of its digits is 5376, while the sum is 30.

The square root of 21222786 is about 4606.8195102478. The cubic root of 21222786 is about 276.8646221229.

Adding to 21222786 its reverse (68722212), we get a palindrome (89944998).

The spelling of 21222786 in words is "twenty-one million, two hundred twenty-two thousand, seven hundred eighty-six".