21643013 has 8 divisors (see below), whose sum is σ = 24776832. Its totient is φ = 18519696.

The previous prime is 21643009. The next prime is 21643021. The reversal of 21643013 is 31034612.

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 21643013 - 2² = 21643009 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 (21643043) 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, 2456 + ... + 7022.

It is an arithmetic number, because the mean of its divisors is an integer number (3097104).

Almost surely, 2^21643013 is an apocalyptic number.

It is an amenable number.

21643013 is a deficient number, since it is larger than the sum of its proper divisors (3133819).

21643013 is an equidigital number, since it uses as much as digits as its factorization.

21643013 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 5251.

The product of its (nonzero) digits is 432, while the sum is 20.

The square root of 21643013 is about 4652.2051760429. The cubic root of 21643013 is about 278.6800673167.

Adding to 21643013 its reverse (31034612), we get a palindrome (52677625).

The spelling of 21643013 in words is "twenty-one million, six hundred forty-three thousand, thirteen".