21911697 has 12 divisors (see below), whose sum is σ = 31717764. Its totient is φ = 14576640.

The previous prime is 21911689. The next prime is 21911713. The reversal of 21911697 is 79611912.

It can be written as a sum of positive squares in 2 ways, for example, as 14814801 + 7096896 = 3849^2 + 2664^2 .

It is not a de Polignac number, because 21911697 - 2³ = 21911689 is a prime.

It is not an unprimeable number, because it can be changed into a prime (21911297) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 2353 + ... + 7025.

It is an arithmetic number, because the mean of its divisors is an integer number (2643147).

Almost surely, 2^21911697 is an apocalyptic number.

It is an amenable number.

21911697 is a deficient number, since it is larger than the sum of its proper divisors (9806067).

21911697 is a wasteful number, since it uses less digits than its factorization.

21911697 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 5200 (or 5197 counting only the distinct ones).

The product of its digits is 6804, while the sum is 36.

The square root of 21911697 is about 4680.9931638489. The cubic root of 21911697 is about 279.8285387326.

The spelling of 21911697 in words is "twenty-one million, nine hundred eleven thousand, six hundred ninety-seven".