21386688 has 112 divisors (see below), whose sum is σ = 61447680. Its totient is φ = 6544384.

The previous prime is 21386671. The next prime is 21386689. The reversal of 21386688 is 88668312.

It is a nude number because it is divisible by every one of its digits.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21386689) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 127981 + ... + 128147.

It is an arithmetic number, because the mean of its divisors is an integer number (548640).

Almost surely, 2^21386688 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 21386688, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (30723840).

21386688 is an abundant number, since it is smaller than the sum of its proper divisors (40060992).

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

21386688 is a wasteful number, since it uses less digits than its factorization.

21386688 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 234 (or 224 counting only the distinct ones).

The product of its digits is 110592, while the sum is 42.

The square root of 21386688 is about 4624.5743587924. The cubic root of 21386688 is about 277.5755301261.

The spelling of 21386688 in words is "twenty-one million, three hundred eighty-six thousand, six hundred eighty-eight".