21539088 has 80 divisors (see below), whose sum is σ = 62763840. Its totient is φ = 7070976.

The previous prime is 21539059. The next prime is 21539101. The reversal of 21539088 is 88093512.

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

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 31195 + ... + 31877.

It is an arithmetic number, because the mean of its divisors is an integer number (784548).

Almost surely, 2^21539088 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 21539088, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (31381920).

21539088 is an abundant number, since it is smaller than the sum of its proper divisors (41224752).

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

21539088 is a wasteful number, since it uses less digits than its factorization.

21539088 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 773 (or 761 counting only the distinct ones).

The product of its (nonzero) digits is 17280, while the sum is 36.

The square root of 21539088 is about 4641.0223011746. The cubic root of 21539088 is about 278.2332979418.

The spelling of 21539088 in words is "twenty-one million, five hundred thirty-nine thousand, eighty-eight".