21658272 has 96 divisors (see below), whose sum is σ = 62923392. Its totient is φ = 6488064.

The previous prime is 21658261. The next prime is 21658277. The reversal of 21658272 is 27285612.

It is a tau number, because it is divible by the number of its divisors (96).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21658277) 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, 37248 + ... + 37824.

It is an arithmetic number, because the mean of its divisors is an integer number (655452).

Almost surely, 2^21658272 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21658272, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (31461696).

21658272 is an abundant number, since it is smaller than the sum of its proper divisors (41265120).

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

21658272 is a wasteful number, since it uses less digits than its factorization.

21658272 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 630 (or 622 counting only the distinct ones).

The product of its digits is 13440, while the sum is 33.

The square root of 21658272 is about 4653.8448620469. The cubic root of 21658272 is about 278.7455446478.

The spelling of 21658272 in words is "twenty-one million, six hundred fifty-eight thousand, two hundred seventy-two".