921609 has 12 divisors (see below), whose sum is σ = 1433796. Its totient is φ = 567072.

The previous prime is 921601. The next prime is 921611. The reversal of 921609 is 906129.

It is a happy number.

It can be written as a sum of positive squares in 2 ways, for example, as 138384 + 783225 = 372^2 + 885^2 .

It is not a de Polignac number, because 921609 - 2³ = 921601 is a prime.

It is an Ulam 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 11 ways as a sum of consecutive naturals, for example, 3822 + ... + 4055.

It is an arithmetic number, because the mean of its divisors is an integer number (119483).

921609 is a Friedman number, since it can be written as (96*10)^2+9, using all its digits and the basic arithmetic operations.

2⁹²¹⁶⁰⁹ is an apocalyptic number.

It is an amenable number.

921609 is a deficient number, since it is larger than the sum of its proper divisors (512187).

921609 is a wasteful number, since it uses less digits than its factorization.

921609 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 7896 (or 7893 counting only the distinct ones).

The product of its (nonzero) digits is 972, while the sum is 27.

The square root of 921609 is about 960.0046874886. The cubic root of 921609 is about 97.3155487095.

It can be divided in two parts, 9 and 21609, that multiplied together give a 4-th power (194481 = 21⁴).

The spelling of 921609 in words is "nine hundred twenty-one thousand, six hundred nine".