21704661 has 24 divisors (see below), whose sum is σ = 34369920. Its totient is φ = 13089600.

The previous prime is 21704653. The next prime is 21704671. The reversal of 21704661 is 16640712.

It is not a de Polignac number, because 21704661 - 2³ = 21704653 is a prime.

It is a Curzon number.

It is a congruent number.

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

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 26425 + ... + 27233.

It is an arithmetic number, because the mean of its divisors is an integer number (1432080).

Almost surely, 2^21704661 is an apocalyptic number.

It is an amenable number.

21704661 is a deficient number, since it is larger than the sum of its proper divisors (12665259).

21704661 is a wasteful number, since it uses less digits than its factorization.

21704661 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1097 (or 1094 counting only the distinct ones).

The product of its (nonzero) digits is 2016, while the sum is 27.

The square root of 21704661 is about 4658.8261397052. The cubic root of 21704661 is about 278.9444141006.

The spelling of 21704661 in words is "twenty-one million, seven hundred four thousand, six hundred sixty-one".