21254688 has 144 divisors (see below), whose sum is σ = 74483136. Its totient is φ = 5598720.

The previous prime is 21254677. The next prime is 21254689. The reversal of 21254688 is 88645212.

It is a tau number, because it is divible by the number of its divisors (144).

It is a Harshad number since it is a multiple of its sum of digits (36).

It is not an unprimeable number, because it can be changed into a prime (21254689) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (7) of ones.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 25803 + ... + 26613.

It is an arithmetic number, because the mean of its divisors is an integer number (517244).

Almost surely, 2^21254688 is an apocalyptic number.

21254688 is a gapful number since it is divisible by the number (28) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21254688, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (37241568).

21254688 is an abundant number, since it is smaller than the sum of its proper divisors (53228448).

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

21254688 is a wasteful number, since it uses less digits than its factorization.

21254688 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 847 (or 836 counting only the distinct ones).

The product of its digits is 30720, while the sum is 36.

The square root of 21254688 is about 4610.2806855982. The cubic root of 21254688 is about 277.0032799031.

The spelling of 21254688 in words is "twenty-one million, two hundred fifty-four thousand, six hundred eighty-eight".