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10021 = 11911

10021 has 4 divisors (see below), whose sum is σ = 10944. Its totient is φ = 9100.

The previous prime is 10009. The next prime is 10037. The reversal of 10021 is 12001.

Adding to 10021 its reverse (12001), we get a palindrome (22022).

Multipling 10021 by its reverse (12001), we get a palindrome (120262021).

It can be divided in two parts, 100 and 21, that added together give a palindrome (121).

10021 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

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, and also an emirpimes, since its reverse is a distinct semiprime: 12001 = 111091.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2k-10021 is a prime.

It is a Duffinian number.

It is a plaindrome in base 8.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (10061) 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, 445 + ... + 466.

It is an arithmetic number, because the mean of its divisors is an integer number (2736).

210021 is an apocalyptic number.

10021 is a gapful number since it is divisible by the number (11) formed by its first and last digit.

It is an amenable number.

10021 is a deficient number, since it is larger than the sum of its proper divisors (923).

10021 is an equidigital number, since it uses as much as digits as its factorization.

10021 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 922.

The product of its (nonzero) digits is 2, while the sum is 4.

The square root of 10021 is about 100.1049449328. The cubic root of 10021 is about 21.5594173987.

The spelling of 10021 in words is "ten thousand, twenty-one", and thus it is an iban number.

Divisors: 1 11 911 10021