21708693 has 6 divisors (see below), whose sum is σ = 31357014. Its totient is φ = 14472456.

The previous prime is 21708671. The next prime is 21708703. The reversal of 21708693 is 39680712.

It can be written as a sum of positive squares in only one way, i.e., 16793604 + 4915089 = 4098^2 + 2217^2 .

It is not a de Polignac number, because 21708693 - 2⁶ = 21708629 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21708623) by changing a digit.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 1206030 + ... + 1206047.

It is an arithmetic number, because the mean of its divisors is an integer number (5226169).

Almost surely, 2^21708693 is an apocalyptic number.

It is an amenable number.

21708693 is a deficient number, since it is larger than the sum of its proper divisors (9648321).

21708693 is a wasteful number, since it uses less digits than its factorization.

21708693 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2412083 (or 2412080 counting only the distinct ones).

The product of its (nonzero) digits is 18144, while the sum is 36.

The square root of 21708693 is about 4659.2588466407. The cubic root of 21708693 is about 278.9616858783.

The spelling of 21708693 in words is "twenty-one million, seven hundred eight thousand, six hundred ninety-three".