21704641 has 4 divisors (see below), whose sum is σ = 24805312. Its totient is φ = 18603972.

The previous prime is 21704633. The next prime is 21704653. The reversal of 21704641 is 14640712.

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 21704641 - 2³ = 21704633 is a prime.

It is not an unprimeable number, because it can be changed into a prime (21704611) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 1550325 + ... + 1550338.

It is an arithmetic number, because the mean of its divisors is an integer number (6201328).

Almost surely, 2^21704641 is an apocalyptic number.

It is an amenable number.

21704641 is a deficient number, since it is larger than the sum of its proper divisors (3100671).

21704641 is an equidigital number, since it uses as much as digits as its factorization.

21704641 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3100670.

The product of its (nonzero) digits is 1344, while the sum is 25.

The square root of 21704641 is about 4658.8239932412. The cubic root of 21704641 is about 278.9443284218.

The spelling of 21704641 in words is "twenty-one million, seven hundred four thousand, six hundred forty-one".