21438887 has 12 divisors (see below), whose sum is σ = 23518656. Its totient is φ = 19518720.

The previous prime is 21438881. The next prime is 21438913. The reversal of 21438887 is 78883412.

It is not a de Polignac number, because 21438887 - 2¹⁶ = 21373351 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 (21438881) 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, 7763 + ... + 10155.

It is an arithmetic number, because the mean of its divisors is an integer number (1959888).

Almost surely, 2^21438887 is an apocalyptic number.

21438887 is a deficient number, since it is larger than the sum of its proper divisors (2079769).

21438887 is a wasteful number, since it uses less digits than its factorization.

21438887 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2458 (or 2441 counting only the distinct ones).

The product of its digits is 86016, while the sum is 41.

The square root of 21438887 is about 4630.2145738616. The cubic root of 21438887 is about 277.8011750544.

The spelling of 21438887 in words is "twenty-one million, four hundred thirty-eight thousand, eight hundred eighty-seven".