21206489 has 8 divisors (see below), whose sum is σ = 22392000. Its totient is φ = 20027952.

The previous prime is 21206477. The next prime is 21206491. The reversal of 21206489 is 98460212.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 21206489 - 2⁸ = 21206233 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21206189) by changing a digit.

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, 5267 + ... + 8375.

It is an arithmetic number, because the mean of its divisors is an integer number (2799000).

Almost surely, 2^21206489 is an apocalyptic number.

It is an amenable number.

21206489 is a deficient number, since it is larger than the sum of its proper divisors (1185511).

21206489 is a wasteful number, since it uses less digits than its factorization.

21206489 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3487.

The product of its (nonzero) digits is 6912, while the sum is 32.

The square root of 21206489 is about 4605.0503797461. The cubic root of 21206489 is about 276.7937357624.

The spelling of 21206489 in words is "twenty-one million, two hundred six thousand, four hundred eighty-nine".