21911709 has 12 divisors (see below), whose sum is σ = 30543296. Its totient is φ = 13971672.

The previous prime is 21911689. The next prime is 21911713. The reversal of 21911709 is 90711912.

It is not a de Polignac number, because 21911709 - 2⁷ = 21911581 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 (21911789) 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 11 ways as a sum of consecutive naturals, for example, 5317 + ... + 8490.

Almost surely, 2^21911709 is an apocalyptic number.

It is an amenable number.

21911709 is a deficient number, since it is larger than the sum of its proper divisors (8631587).

21911709 is a wasteful number, since it uses less digits than its factorization.

21911709 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 13856 (or 13833 counting only the distinct ones).

The product of its (nonzero) digits is 1134, while the sum is 30.

The square root of 21911709 is about 4680.9944456280. The cubic root of 21911709 is about 279.8285898155.

The spelling of 21911709 in words is "twenty-one million, nine hundred eleven thousand, seven hundred nine".