21223155 has 16 divisors (see below), whose sum is σ = 34149024. Its totient is φ = 11255040.

The previous prime is 21223141. The next prime is 21223159. The reversal of 21223155 is 55132212.

It is not a de Polignac number, because 21223155 - 2⁶ = 21223091 is a prime.

It is not an unprimeable number, because it can be changed into a prime (21223159) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 1194 + ... + 6623.

It is an arithmetic number, because the mean of its divisors is an integer number (2134314).

Almost surely, 2^21223155 is an apocalyptic number.

21223155 is a deficient number, since it is larger than the sum of its proper divisors (12925869).

21223155 is a wasteful number, since it uses less digits than its factorization.

21223155 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 8006.

The product of its digits is 600, while the sum is 21.

The square root of 21223155 is about 4606.8595593962. The cubic root of 21223155 is about 276.8662267261.

Adding to 21223155 its reverse (55132212), we get a palindrome (76355367).

The spelling of 21223155 in words is "twenty-one million, two hundred twenty-three thousand, one hundred fifty-five".