21161140 has 144 divisors (see below), whose sum is σ = 61133184. Its totient is φ = 6048000.

The previous prime is 21161137. The next prime is 21161191. The reversal of 21161140 is 4116112.

It is a congruent number.

It is an unprimeable number.

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 47 ways as a sum of consecutive naturals, for example, 140065 + ... + 140215.

It is an arithmetic number, because the mean of its divisors is an integer number (424536).

Almost surely, 2^21161140 is an apocalyptic number.

21161140 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21161140, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (30566592).

21161140 is an abundant number, since it is smaller than the sum of its proper divisors (39972044).

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

21161140 is a wasteful number, since it uses less digits than its factorization.

21161140 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 198 (or 189 counting only the distinct ones).

The product of its (nonzero) digits is 48, while the sum is 16.

The square root of 21161140 is about 4600.1239113746. The cubic root of 21161140 is about 276.5962918374.

Adding to 21161140 its reverse (4116112), we get a palindrome (25277252).

It can be divided in two parts, 21 and 161140, that added together give a palindrome (161161).

The spelling of 21161140 in words is "twenty-one million, one hundred sixty-one thousand, one hundred forty".