21404289 has 16 divisors (see below), whose sum is σ = 29336832. Its totient is φ = 13876368.

The previous prime is 21404269. The next prime is 21404303. The reversal of 21404289 is 98240412.

It is not a de Polignac number, because 21404289 - 2¹⁹ = 20880001 is a prime.

It is not an unprimeable number, because it can be changed into a prime (21404269) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 16042 + ... + 17324.

It is an arithmetic number, because the mean of its divisors is an integer number (1833552).

Almost surely, 2^21404289 is an apocalyptic number.

It is an amenable number.

21404289 is a deficient number, since it is larger than the sum of its proper divisors (7932543).

21404289 is a wasteful number, since it uses less digits than its factorization.

21404289 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1436.

The product of its (nonzero) digits is 4608, while the sum is 30.

The square root of 21404289 is about 4626.4769533631. The cubic root of 21404289 is about 277.6516564101.

The spelling of 21404289 in words is "twenty-one million, four hundred four thousand, two hundred eighty-nine".