21864641 has 8 divisors (see below), whose sum is σ = 22623744. Its totient is φ = 21108960.

The previous prime is 21864617. The next prime is 21864653. The reversal of 21864641 is 14646812.

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 21864641 - 2¹⁰ = 21863617 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 21864598 and 21864607.

It is not an unprimeable number, because it can be changed into a prime (21864341) 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, 25085 + ... + 25941.

It is an arithmetic number, because the mean of its divisors is an integer number (2827968).

Almost surely, 2^21864641 is an apocalyptic number.

It is an amenable number.

21864641 is a deficient number, since it is larger than the sum of its proper divisors (759103).

21864641 is an equidigital number, since it uses as much as digits as its factorization.

21864641 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1711.

The product of its digits is 9216, while the sum is 32.

The square root of 21864641 is about 4675.9641786481. The cubic root of 21864641 is about 279.6280818880.

The spelling of 21864641 in words is "twenty-one million, eight hundred sixty-four thousand, six hundred forty-one".