21489871 has 12 divisors (see below), whose sum is σ = 23519160. Its totient is φ = 19624800.

The previous prime is 21489833. The next prime is 21489877. The reversal of 21489871 is 17898412.

It is a happy number.

It is not a de Polignac number, because 21489871 - 2⁹ = 21489359 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21489877) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 16440 + ... + 17698.

It is an arithmetic number, because the mean of its divisors is an integer number (1959930).

Almost surely, 2^21489871 is an apocalyptic number.

21489871 is a deficient number, since it is larger than the sum of its proper divisors (2029289).

21489871 is a wasteful number, since it uses less digits than its factorization.

21489871 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1386 (or 1373 counting only the distinct ones).

The product of its digits is 32256, while the sum is 40.

The square root of 21489871 is about 4635.7168809150. The cubic root of 21489871 is about 278.0212145017.

The spelling of 21489871 in words is "twenty-one million, four hundred eighty-nine thousand, eight hundred seventy-one".