921921 has 32 divisors (see below), whose sum is σ = 1655808. Its totient is φ = 440640.

The previous prime is 921919. The next prime is 921931. The reversal of 921921 is 129129.

It is not a de Polignac number, because 921921 - 2¹ = 921919 is a prime.

It is a Curzon number.

It is a junction number, because it is equal to n+sod(n) for n = 921891 and 921900.

It is not an unprimeable number, because it can be changed into a prime (921901) 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 31 ways as a sum of consecutive naturals, for example, 2850 + ... + 3156.

It is an arithmetic number, because the mean of its divisors is an integer number (51744).

2⁹²¹⁹²¹ is an apocalyptic number.

921921 is a gapful number since it is divisible by the number (91) formed by its first and last digit.

It is an amenable number.

921921 is a deficient number, since it is larger than the sum of its proper divisors (733887).

921921 is a wasteful number, since it uses less digits than its factorization.

921921 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 341.

The product of its digits is 324, while the sum is 24.

The square root of 921921 is about 960.1671729444. The cubic root of 921921 is about 97.3265291526.

The spelling of 921921 in words is "nine hundred twenty-one thousand, nine hundred twenty-one".