21871280 has 40 divisors (see below), whose sum is σ = 53530800. Its totient is φ = 8287488.

The previous prime is 21871273. The next prime is 21871303. The reversal of 21871280 is 8217812.

It is a tau number, because it is divible by the number of its divisors (40).

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 7 ways as a sum of consecutive naturals, for example, 5675 + ... + 8714.

It is an arithmetic number, because the mean of its divisors is an integer number (1338270).

Almost surely, 2^21871280 is an apocalyptic number.

21871280 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21871280 is an abundant number, since it is smaller than the sum of its proper divisors (31659520).

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

21871280 is a wasteful number, since it uses less digits than its factorization.

21871280 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 14421 (or 14415 counting only the distinct ones).

The product of its (nonzero) digits is 1792, while the sum is 29.

The square root of 21871280 is about 4676.6740318307. The cubic root of 21871280 is about 279.6563812012.

The spelling of 21871280 in words is "twenty-one million, eight hundred seventy-one thousand, two hundred eighty".