21507889 has 8 divisors (see below), whose sum is σ = 23203712. Its totient is φ = 19818000.

The previous prime is 21507881. The next prime is 21507911. The reversal of 21507889 is 98870512.

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 21507889 - 2³ = 21507881 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21507881) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 8662 + ... + 10864.

It is an arithmetic number, because the mean of its divisors is an integer number (2900464).

Almost surely, 2^21507889 is an apocalyptic number.

It is an amenable number.

21507889 is a deficient number, since it is larger than the sum of its proper divisors (1695823).

21507889 is a wasteful number, since it uses less digits than its factorization.

21507889 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2967.

The product of its (nonzero) digits is 40320, while the sum is 40.

The square root of 21507889 is about 4637.6598624737. The cubic root of 21507889 is about 278.0988943052.

The spelling of 21507889 in words is "twenty-one million, five hundred seven thousand, eight hundred eighty-nine".