102721 has 4 divisors (see below), whose sum is σ = 103600. Its totient is φ = 101844.

The previous prime is 102701. The next prime is 102761. The reversal of 102721 is 127201.

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 a brilliant number, because the two primes have the same length, and also an emirpimes, since its reverse is a distinct semiprime: 127201 = 131 ⋅971.

It is a cyclic number.

It is not a de Polignac number, because 102721 - 2⁷ = 102593 is a prime.

It is an Ulam number.

It is the 321-st Hogben number.

It is a Duffinian number.

102721 is a lucky number.

It is not an unprimeable number, because it can be changed into a prime (102701) by changing a digit.

It is a nontrivial repunit in base 320.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 231 + ... + 508.

It is an arithmetic number, because the mean of its divisors is an integer number (25900).

2¹⁰²⁷²¹ is an apocalyptic number.

It is an amenable number.

102721 is a deficient number, since it is larger than the sum of its proper divisors (879).

102721 is an equidigital number, since it uses as much as digits as its factorization.

102721 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 878.

The product of its (nonzero) digits is 28, while the sum is 13.

The square root of 102721 is about 320.5011700447. The cubic root of 102721 is about 46.8331187398.

Adding to 102721 its reverse (127201), we get a palindrome (229922).

The spelling of 102721 in words is "one hundred two thousand, seven hundred twenty-one", and thus it is an iban number.