21911671 has 4 divisors (see below), whose sum is σ = 22446144. Its totient is φ = 21377200.

The previous prime is 21911651. The next prime is 21911683. The reversal of 21911671 is 17611912.

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 21911671 - 2⁹ = 21911159 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21911611) 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, 267175 + ... + 267256.

It is an arithmetic number, because the mean of its divisors is an integer number (5611536).

Almost surely, 2^21911671 is an apocalyptic number.

21911671 is a deficient number, since it is larger than the sum of its proper divisors (534473).

21911671 is an equidigital number, since it uses as much as digits as its factorization.

21911671 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 534472.

The product of its digits is 756, while the sum is 28.

The square root of 21911671 is about 4680.9903866596. The cubic root of 21911671 is about 279.8284280528.

The spelling of 21911671 in words is "twenty-one million, nine hundred eleven thousand, six hundred seventy-one".