872121 has 4 divisors (see below), whose sum is σ = 1162832. Its totient is φ = 581412.

The previous prime is 872107. The next prime is 872129. The reversal of 872121 is 121278.

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 872121 - 2⁵ = 872089 is a prime.

It is a D-number.

It is an alternating number because its digits alternate between even and odd.

It is a Duffinian number.

It is a Curzon number.

872121 is a lucky number.

It is not an unprimeable number, because it can be changed into a prime (872129) 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, 145351 + ... + 145356.

It is an arithmetic number, because the mean of its divisors is an integer number (290708).

2⁸⁷²¹²¹ is an apocalyptic number.

It is an amenable number.

872121 is a deficient number, since it is larger than the sum of its proper divisors (290711).

872121 is a wasteful number, since it uses less digits than its factorization.

872121 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 290710.

The product of its digits is 224, while the sum is 21.

The square root of 872121 is about 933.8741885286. The cubic root of 872121 is about 95.5415423735.

Adding to 872121 its reverse (121278), we get a palindrome (993399).

The spelling of 872121 in words is "eight hundred seventy-two thousand, one hundred twenty-one".