921521 has 4 divisors (see below), whose sum is σ = 937200. Its totient is φ = 905844.

The previous prime is 921517. The next prime is 921523. The reversal of 921521 is 125129.

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: 125129 = 157 ⋅797.

It is a cyclic number.

It is not a de Polignac number, because 921521 - 2² = 921517 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 921493 and 921502.

It is not an unprimeable number, because it can be changed into a prime (921523) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 7751 + ... + 7868.

It is an arithmetic number, because the mean of its divisors is an integer number (234300).

2⁹²¹⁵²¹ is an apocalyptic number.

It is an amenable number.

921521 is a deficient number, since it is larger than the sum of its proper divisors (15679).

921521 is a wasteful number, since it uses less digits than its factorization.

921521 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 15678.

The product of its digits is 180, while the sum is 20.

The square root of 921521 is about 959.9588532849. The cubic root of 921521 is about 97.3124512134.

The spelling of 921521 in words is "nine hundred twenty-one thousand, five hundred twenty-one".