21563238 has 8 divisors (see below), whose sum is σ = 43126488. Its totient is φ = 7187744.

The previous prime is 21563237. The next prime is 21563249. The reversal of 21563238 is 83236512.

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

21563238 is an admirable number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21563237) 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 3 ways as a sum of consecutive naturals, for example, 1796931 + ... + 1796942.

It is an arithmetic number, because the mean of its divisors is an integer number (5390811).

Almost surely, 2^21563238 is an apocalyptic number.

21563238 is a primitive abundant number, since it is smaller than the sum of its proper divisors, none of which is abundant.

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

21563238 is a wasteful number, since it uses less digits than its factorization.

21563238 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3593878.

The product of its digits is 8640, while the sum is 30.

The square root of 21563238 is about 4643.6233697405. The cubic root of 21563238 is about 278.3372457727.

The spelling of 21563238 in words is "twenty-one million, five hundred sixty-three thousand, two hundred thirty-eight".