21881140 has 12 divisors (see below), whose sum is σ = 45950436. Its totient is φ = 8752448.

The previous prime is 21881137. The next prime is 21881143. The reversal of 21881140 is 4118812.

It is an interprime number because it is at equal distance from previous prime (21881137) and next prime (21881143).

It can be written as a sum of positive squares in 2 ways, for example, as 12988816 + 8892324 = 3604^2 + 2982^2 .

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21881143) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 547009 + ... + 547048.

It is an arithmetic number, because the mean of its divisors is an integer number (3829203).

Almost surely, 2^21881140 is an apocalyptic number.

21881140 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21881140 is an abundant number, since it is smaller than the sum of its proper divisors (24069296).

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

21881140 is a wasteful number, since it uses less digits than its factorization.

21881140 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1094066 (or 1094064 counting only the distinct ones).

The product of its (nonzero) digits is 512, while the sum is 25.

The square root of 21881140 is about 4677.7280810239. The cubic root of 21881140 is about 279.6983997396.

Adding to 21881140 its reverse (4118812), we get a palindrome (25999952).

The spelling of 21881140 in words is "twenty-one million, eight hundred eighty-one thousand, one hundred forty".