21381289 has 12 divisors (see below), whose sum is σ = 23275920. Its totient is φ = 19585800.

The previous prime is 21381281. The next prime is 21381307. The reversal of 21381289 is 98218312.

It is not a de Polignac number, because 21381289 - 2³ = 21381281 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21381281) 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, 17674 + ... + 18844.

It is an arithmetic number, because the mean of its divisors is an integer number (1939660).

Almost surely, 2^21381289 is an apocalyptic number.

It is an amenable number.

21381289 is a deficient number, since it is larger than the sum of its proper divisors (1894631).

21381289 is a wasteful number, since it uses less digits than its factorization.

21381289 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1252 (or 1221 counting only the distinct ones).

The product of its digits is 6912, while the sum is 34.

The square root of 21381289 is about 4623.9905925510. The cubic root of 21381289 is about 277.5521704796.

The spelling of 21381289 in words is "twenty-one million, three hundred eighty-one thousand, two hundred eighty-nine".