21591882 has 48 divisors (see below), whose sum is σ = 51361128. Its totient is φ = 6514560.

The previous prime is 21591839. The next prime is 21591893. The reversal of 21591882 is 28819512.

It can be written as a sum of positive squares in 4 ways, for example, as 9418761 + 12173121 = 3069^2 + 3489^2 .

It is an unprimeable number.

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 23 ways as a sum of consecutive naturals, for example, 11532 + ... + 13272.

Almost surely, 2^21591882 is an apocalyptic number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21591882, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (25680564).

21591882 is an abundant number, since it is smaller than the sum of its proper divisors (29769246).

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

21591882 is a wasteful number, since it uses less digits than its factorization.

21591882 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1815 (or 1812 counting only the distinct ones).

The product of its digits is 11520, while the sum is 36.

The square root of 21591882 is about 4646.7065756297. The cubic root of 21591882 is about 278.4604363689.

It can be divided in two parts, 215918 and 82, that added together give a cube (216000 = 60³).

The spelling of 21591882 in words is "twenty-one million, five hundred ninety-one thousand, eight hundred eighty-two".