21385643 has 8 divisors (see below), whose sum is σ = 22698000. Its totient is φ = 20079360.

The previous prime is 21385633. The next prime is 21385649. The reversal of 21385643 is 34658312.

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 21385643 - 2⁴ = 21385627 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21385649) 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, 7223 + ... + 9743.

It is an arithmetic number, because the mean of its divisors is an integer number (2837250).

Almost surely, 2^21385643 is an apocalyptic number.

21385643 is a deficient number, since it is larger than the sum of its proper divisors (1312357).

21385643 is a wasteful number, since it uses less digits than its factorization.

21385643 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3037.

The product of its digits is 17280, while the sum is 32.

The square root of 21385643 is about 4624.4613740413. The cubic root of 21385643 is about 277.5710090715.

The spelling of 21385643 in words is "twenty-one million, three hundred eighty-five thousand, six hundred forty-three".