21077 has 4 divisors (see below), whose sum is σ = 24096. Its totient is φ = 18060.

The previous prime is 21067. The next prime is 21089. The reversal of 21077 is 77012.

It is a happy number.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is not a de Polignac number, because 21077 - 2⁴ = 21061 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21017) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (7) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 1499 + ... + 1512.

It is an arithmetic number, because the mean of its divisors is an integer number (6024).

It is an amenable number.

21077 is a deficient number, since it is larger than the sum of its proper divisors (3019).

21077 is an equidigital number, since it uses as much as digits as its factorization.

21077 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3018.

The product of its (nonzero) digits is 98, while the sum is 17.

The square root of 21077 is about 145.1791996121. The cubic root of 21077 is about 27.6229208184.

Adding to 21077 its reverse (77012), we get a palindrome (98089).

The spelling of 21077 in words is "twenty-one thousand, seventy-seven", and thus it is an iban number.