921605 has 4 divisors (see below), whose sum is σ = 1105932. Its totient is φ = 737280.

The previous prime is 921601. The next prime is 921611. The reversal of 921605 is 506129.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 506129 = 13 ⋅38933.

It can be written as a sum of positive squares in 2 ways, for example, as 564001 + 357604 = 751^2 + 598^2 .

It is not a de Polignac number, because 921605 - 2² = 921601 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (921601) 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, 92156 + ... + 92165.

It is an arithmetic number, because the mean of its divisors is an integer number (276483).

921605 is a Friedman number, since it can be written as (96*10)^2+5, using all its digits and the basic arithmetic operations.

2⁹²¹⁶⁰⁵ is an apocalyptic number.

It is an amenable number.

921605 is a deficient number, since it is larger than the sum of its proper divisors (184327).

921605 is a wasteful number, since it uses less digits than its factorization.

921605 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 184326.

The product of its (nonzero) digits is 540, while the sum is 23.

The square root of 921605 is about 960.0026041631. The cubic root of 921605 is about 97.3154079185.

The spelling of 921605 in words is "nine hundred twenty-one thousand, six hundred five".