21440641 has 4 divisors (see below), whose sum is σ = 21582784. Its totient is φ = 21298500.

The previous prime is 21440609. The next prime is 21440647. The reversal of 21440641 is 14604412.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 21440641 - 2⁵ = 21440609 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21440647) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 70845 + ... + 71146.

It is an arithmetic number, because the mean of its divisors is an integer number (5395696).

Almost surely, 2^21440641 is an apocalyptic number.

It is an amenable number.

21440641 is a deficient number, since it is larger than the sum of its proper divisors (142143).

21440641 is a wasteful number, since it uses less digits than its factorization.

21440641 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 142142.

The product of its (nonzero) digits is 768, while the sum is 22.

The square root of 21440641 is about 4630.4039780563. The cubic root of 21440641 is about 277.8087508515.

The spelling of 21440641 in words is "twenty-one million, four hundred forty thousand, six hundred forty-one".