21143509 has 8 divisors (see below), whose sum is σ = 22182912. Its totient is φ = 20114160.

The previous prime is 21143497. The next prime is 21143533. The reversal of 21143509 is 90534112.

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 21143509 - 2⁵ = 21143477 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 (21143569) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 1987 + ... + 6799.

It is an arithmetic number, because the mean of its divisors is an integer number (2772864).

Almost surely, 2^21143509 is an apocalyptic number.

It is an amenable number.

21143509 is a deficient number, since it is larger than the sum of its proper divisors (1039403).

21143509 is a wasteful number, since it uses less digits than its factorization.

21143509 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 5027.

The product of its (nonzero) digits is 1080, while the sum is 25.

The square root of 21143509 is about 4598.2071506186. The cubic root of 21143509 is about 276.5194524953.

The spelling of 21143509 in words is "twenty-one million, one hundred forty-three thousand, five hundred nine".