21737 has 2 divisors, whose sum is σ = 21738.
Its totient is φ = 21736.
The previous prime is 21727. The next prime is 21739. The reversal of 21737 is 73712.
It is a strong prime.
It can be written as a sum of positive squares in only one way, i.e., 13456 + 8281 = 116^2 + 91^2
It is a cyclic number.
It is not a de Polignac number, because 21737 - 26 = 21673 is a prime.
Together with 21739, it forms a pair of twin primes.
It is a Chen prime.
It is a pancake number, because a pancake can be divided into 21737 parts by 208 straight cuts.
It is an inconsummate number, since it does not exist a number n which divided by its sum of digits gives 21737.
It is not a weakly prime, because it can be changed into another prime (21739) by changing a digit.
It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10868 + 10869.
It is an arithmetic number, because the mean of its divisors is an integer number (10869).
221737 is an apocalyptic number.
It is an amenable number.
21737 is a deficient number, since it is larger than the sum of its proper divisors (1).
21737 is an equidigital number, since it uses as much as digits as its factorization.
21737 is an evil number, because the sum of its binary digits is even.
The product of its digits is 294, while the sum is 20.
The square root of 21737 is about 147.4347313220.
The cubic root of 21737 is about 27.9082883697.
The spelling of 21737 in words is "twenty-one thousand, seven hundred thirty-seven".