21655338 has 32 divisors (see below), whose sum is σ = 44468736. Its totient is φ = 7028208.

The previous prime is 21655327. The next prime is 21655367. The reversal of 21655338 is 83355612.

It is a junction number, because it is equal to n+sod(n) for n = 21655299 and 21655308.

It is an unprimeable number.

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 15 ways as a sum of consecutive naturals, for example, 41145 + ... + 41667.

It is an arithmetic number, because the mean of its divisors is an integer number (1389648).

Almost surely, 2^21655338 is an apocalyptic number.

21655338 is an abundant number, since it is smaller than the sum of its proper divisors (22813398).

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

21655338 is a wasteful number, since it uses less digits than its factorization.

21655338 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 698.

The product of its digits is 21600, while the sum is 33.

The square root of 21655338 is about 4653.5296281425. The cubic root of 21655338 is about 278.7329570576.

It can be divided in two parts, 2165 and 5338, that added together give a triangular number (7503 = T₁₂₂).

The spelling of 21655338 in words is "twenty-one million, six hundred fifty-five thousand, three hundred thirty-eight".