21222690 has 32 divisors (see below), whose sum is σ = 51105600. Its totient is φ = 5640384.

The previous prime is 21222689. The next prime is 21222697. The reversal of 21222690 is 9622212.

It is a super-2 number, since 2×21222690² = 900805141672200, which contains 22 as substring.

It is a self number, because there is not a number n which added to its sum of digits gives 21222690.

It is not an unprimeable number, because it can be changed into a prime (21222697) 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 15 ways as a sum of consecutive naturals, for example, 9457 + ... + 11483.

It is an arithmetic number, because the mean of its divisors is an integer number (1597050).

Almost surely, 2^21222690 is an apocalyptic number.

21222690 is an abundant number, since it is smaller than the sum of its proper divisors (29882910).

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

21222690 is a wasteful number, since it uses less digits than its factorization.

21222690 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2386.

The product of its (nonzero) digits is 864, while the sum is 24.

The square root of 21222690 is about 4606.8090909001. The cubic root of 21222690 is about 276.8642046621.

It can be divided in two parts, 21222 and 690, that added together give a palindrome (21912).

The spelling of 21222690 in words is "twenty-one million, two hundred twenty-two thousand, six hundred ninety".