21423688 has 64 divisors (see below), whose sum is σ = 48121920. Its totient is φ = 8812800.

The previous prime is 21423679. The next prime is 21423709. The reversal of 21423688 is 88632412.

It is an unprimeable number.

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, 69631 + ... + 69937.

It is an arithmetic number, because the mean of its divisors is an integer number (751905).

Almost surely, 2^21423688 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 21423688, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (24060960).

21423688 is an abundant number, since it is smaller than the sum of its proper divisors (26698232).

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

21423688 is a wasteful number, since it uses less digits than its factorization.

21423688 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 398 (or 394 counting only the distinct ones).

The product of its digits is 18432, while the sum is 34.

The square root of 21423688 is about 4628.5729982361. The cubic root of 21423688 is about 277.7355109142.

The spelling of 21423688 in words is "twenty-one million, four hundred twenty-three thousand, six hundred eighty-eight".