21861132 has 48 divisors (see below), whose sum is σ = 53813760. Its totient is φ = 6893568.

The previous prime is 21861127. The next prime is 21861137. The reversal of 21861132 is 23116812.

It is an interprime number because it is at equal distance from previous prime (21861127) and next prime (21861137).

It is not an unprimeable number, because it can be changed into a prime (21861137) by changing a digit.

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, 28044 + ... + 28812.

It is an arithmetic number, because the mean of its divisors is an integer number (1121120).

Almost surely, 2^21861132 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 21861132, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (26906880).

21861132 is an abundant number, since it is smaller than the sum of its proper divisors (31952628).

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

21861132 is a wasteful number, since it uses less digits than its factorization.

21861132 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 902 (or 900 counting only the distinct ones).

The product of its digits is 576, while the sum is 24.

The square root of 21861132 is about 4675.5889468601. The cubic root of 21861132 is about 279.6131221571.

Adding to 21861132 its reverse (23116812), we get a palindrome (44977944).

The spelling of 21861132 in words is "twenty-one million, eight hundred sixty-one thousand, one hundred thirty-two".