21558132 has 36 divisors (see below), whose sum is σ = 55393156. Its totient is φ = 7067520.

The previous prime is 21558109. The next prime is 21558133. The reversal of 21558132 is 23185512.

It is a happy number.

It can be written as a sum of positive squares in 2 ways, for example, as 11861136 + 9696996 = 3444^2 + 3114^2 .

It is a tau number, because it is divible by the number of its divisors (36).

It is a junction number, because it is equal to n+sod(n) for n = 21558096 and 21558105.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21558133) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 2713 + ... + 7104.

Almost surely, 2^21558132 is an apocalyptic number.

It is an amenable number.

21558132 is an abundant number, since it is smaller than the sum of its proper divisors (33835024).

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

21558132 is a wasteful number, since it uses less digits than its factorization.

21558132 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 9888 (or 9883 counting only the distinct ones).

The product of its digits is 2400, while the sum is 27.

The square root of 21558132 is about 4643.0735510005. The cubic root of 21558132 is about 278.3152747038.

The spelling of 21558132 in words is "twenty-one million, five hundred fifty-eight thousand, one hundred thirty-two".