21404671 has 4 divisors (see below), whose sum is σ = 21536152. Its totient is φ = 21273192.

The previous prime is 21404653. The next prime is 21404681. The reversal of 21404671 is 17640412.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 21404671 - 2⁷ = 21404543 is a prime.

It is a Duffinian number.

It is a plaindrome in base 16.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21404681) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 65496 + ... + 65821.

It is an arithmetic number, because the mean of its divisors is an integer number (5384038).

Almost surely, 2^21404671 is an apocalyptic number.

21404671 is a deficient number, since it is larger than the sum of its proper divisors (131481).

21404671 is a wasteful number, since it uses less digits than its factorization.

21404671 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 131480.

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

The square root of 21404671 is about 4626.5182372925. The cubic root of 21404671 is about 277.6533081398.

The spelling of 21404671 in words is "twenty-one million, four hundred four thousand, six hundred seventy-one".