691445 has 4 divisors (see below), whose sum is σ = 829740. Its totient is φ = 553152.

The previous prime is 691433. The next prime is 691451. The reversal of 691445 is 544196.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 454276 + 237169 = 674^2 + 487^2 .

It is a cyclic number.

It is not a de Polignac number, because 691445 - 2⁶ = 691381 is a prime.

It is a Curzon number.

It is a congruent number.

It is an unprimeable number.

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, 69140 + ... + 69149.

It is an arithmetic number, because the mean of its divisors is an integer number (207435).

2⁶⁹¹⁴⁴⁵ is an apocalyptic number.

It is an amenable number.

691445 is a deficient number, since it is larger than the sum of its proper divisors (138295).

691445 is a wasteful number, since it uses less digits than its factorization.

691445 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 138294.

The product of its digits is 4320, while the sum is 29.

The square root of 691445 is about 831.5317191785. The cubic root of 691445 is about 88.4272013504.

The spelling of 691445 in words is "six hundred ninety-one thousand, four hundred forty-five".