21686683 has 4 divisors (see below), whose sum is σ = 21696328. Its totient is φ = 21677040.

The previous prime is 21686671. The next prime is 21686741. The reversal of 21686683 is 38668612.

It is a semiprime because it is the product of two primes, and also a brilliant number, because the two primes have the same length.

It is a cyclic number.

It is not a de Polignac number, because 21686683 - 2¹³ = 21678491 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21686633) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 535 + ... + 6607.

It is an arithmetic number, because the mean of its divisors is an integer number (5424082).

Almost surely, 2^21686683 is an apocalyptic number.

21686683 is a deficient number, since it is larger than the sum of its proper divisors (9645).

21686683 is an equidigital number, since it uses as much as digits as its factorization.

21686683 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 9644.

The product of its digits is 82944, while the sum is 40.

The square root of 21686683 is about 4656.8962840072. The cubic root of 21686683 is about 278.8673761482.

The spelling of 21686683 in words is "twenty-one million, six hundred eighty-six thousand, six hundred eighty-three".