21641641 has 8 divisors (see below), whose sum is σ = 25139264. Its totient is φ = 18245520.

The previous prime is 21641611. The next prime is 21641671. The reversal of 21641641 is 14614612.

It is an interprime number because it is at equal distance from previous prime (21641611) and next prime (21641671).

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 21641641 - 2¹⁹ = 21117353 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21641611) 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, 24915 + ... + 25768.

It is an arithmetic number, because the mean of its divisors is an integer number (3142408).

Almost surely, 2^21641641 is an apocalyptic number.

It is an amenable number.

21641641 is a deficient number, since it is larger than the sum of its proper divisors (3497623).

21641641 is an equidigital number, since it uses as much as digits as its factorization.

21641641 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 50751.

The product of its digits is 1152, while the sum is 25.

The square root of 21641641 is about 4652.0577167529. The cubic root of 21641641 is about 278.6741784704.

The spelling of 21641641 in words is "twenty-one million, six hundred forty-one thousand, six hundred forty-one".