21542688 has 72 divisors (see below), whose sum is σ = 61837776. Its totient is φ = 7113600.

The previous prime is 21542687. The next prime is 21542761. The reversal of 21542688 is 88624512.

It is a tau number, because it is divible by the number of its divisors (72).

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 (21542681) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 37443 + ... + 38013.

It is an arithmetic number, because the mean of its divisors is an integer number (858858).

Almost surely, 2^21542688 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 21542688, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (30918888).

21542688 is an abundant number, since it is smaller than the sum of its proper divisors (40295088).

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

21542688 is a wasteful number, since it uses less digits than its factorization.

21542688 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 718 (or 707 counting only the distinct ones).

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

The square root of 21542688 is about 4641.4101305530. The cubic root of 21542688 is about 278.2487981969.

The spelling of 21542688 in words is "twenty-one million, five hundred forty-two thousand, six hundred eighty-eight".