21686693 has 16 divisors (see below), whose sum is σ = 26196480. Its totient is φ = 17558016.

The previous prime is 21686671. The next prime is 21686741. The reversal of 21686693 is 39668612.

It is not a de Polignac number, because 21686693 - 2¹⁴ = 21670309 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 21686693.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21686633) 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 15 ways as a sum of consecutive naturals, for example, 8405 + ... + 10677.

It is an arithmetic number, because the mean of its divisors is an integer number (1637280).

Almost surely, 2^21686693 is an apocalyptic number.

It is an amenable number.

21686693 is a deficient number, since it is larger than the sum of its proper divisors (4509787).

21686693 is a wasteful number, since it uses less digits than its factorization.

21686693 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2356.

The product of its digits is 93312, while the sum is 41.

The square root of 21686693 is about 4656.8973576835. The cubic root of 21686693 is about 278.8674190113.

The spelling of 21686693 in words is "twenty-one million, six hundred eighty-six thousand, six hundred ninety-three".