21081880 has 32 divisors (see below), whose sum is σ = 48243600. Its totient is φ = 8288896.

The previous prime is 21081877. The next prime is 21081881. The reversal of 21081880 is 8818012.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21081881) 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 7 ways as a sum of consecutive naturals, for example, 2107 + ... + 6826.

Almost surely, 2^21081880 is an apocalyptic number.

21081880 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21081880 is an abundant number, since it is smaller than the sum of its proper divisors (27161720).

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

21081880 is a wasteful number, since it uses less digits than its factorization.

21081880 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 9003 (or 8999 counting only the distinct ones).

The product of its (nonzero) digits is 1024, while the sum is 28.

The square root of 21081880 is about 4591.5008439507. The cubic root of 21081880 is about 276.2505251725.

Adding to 21081880 its reverse (8818012), we get a palindrome (29899892).

The spelling of 21081880 in words is "twenty-one million, eighty-one thousand, eight hundred eighty".