21222555 has 8 divisors (see below), whose sum is σ = 33956112. Its totient is φ = 11318688.

The previous prime is 21222529. The next prime is 21222557. The reversal of 21222555 is 55522212.

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 21222555 - 2⁹ = 21222043 is a prime.

It is not an unprimeable number, because it can be changed into a prime (21222557) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 707404 + ... + 707433.

It is an arithmetic number, because the mean of its divisors is an integer number (4244514).

Almost surely, 2^21222555 is an apocalyptic number.

21222555 is a deficient number, since it is larger than the sum of its proper divisors (12733557).

21222555 is a wasteful number, since it uses less digits than its factorization.

21222555 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1414845.

The product of its digits is 2000, while the sum is 24.

The square root of 21222555 is about 4606.7944386525. The cubic root of 21222555 is about 276.8636176057.

Adding to 21222555 its reverse (55522212), we get a palindrome (76744767).

The spelling of 21222555 in words is "twenty-one million, two hundred twenty-two thousand, five hundred fifty-five".