21677 has 4 divisors (see below), whose sum is σ = 22140.
Its totient is φ = 21216.
The previous prime is 21673. The next prime is 21683. The reversal of 21677 is 77612.
21677 = 842 + 852 + 862.
It is a happy number.
It is a semiprime because it is the product of two primes.
It can be written as a sum of positive squares in 2 ways, for example, as 17956 + 3721 = 134^2 + 61^2
It is a cyclic number.
It is not a de Polignac number, because 21677 - 22 = 21673 is a prime.
It is a Duffinian number.
It is a nialpdrome in base 15.
It is a congruent number.
It is an inconsummate number, since it does not exist a number n which divided by its sum of digits gives 21677.
It is not an unprimeable number, because it can be changed into a prime (21673) 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, 152 + ... + 257.
It is an arithmetic number, because the mean of its divisors is an integer number (5535).
221677 is an apocalyptic number.
It is an amenable number.
21677 is a deficient number, since it is larger than the sum of its proper divisors (463).
21677 is an equidigital number, since it uses as much as digits as its factorization.
21677 is an evil number, because the sum of its binary digits is even.
The sum of its prime factors is 462.
The product of its digits is 588, while the sum is 23.
The square root of 21677 is about 147.2311108428.
The cubic root of 21677 is about 27.8825865654.
The spelling of 21677 in words is "twenty-one thousand, six hundred seventy-seven".