691345 has 12 divisors (see below), whose sum is σ = 861084. Its totient is φ = 532800.

The previous prime is 691343. The next prime is 691349. The reversal of 691345 is 543196.

It can be written as a sum of positive squares in 6 ways, for example, as 271441 + 419904 = 521^2 + 648^2 .

It is not a de Polignac number, because 691345 - 2¹ = 691343 is a prime.

It is a Duffinian number.

Its product of digits (3240) is a multiple of the sum of its prime factors (180).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (691343) 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, 6795 + ... + 6895.

It is an arithmetic number, because the mean of its divisors is an integer number (71757).

2⁶⁹¹³⁴⁵ is an apocalyptic number.

It is an amenable number.

691345 is a deficient number, since it is larger than the sum of its proper divisors (169739).

691345 is a wasteful number, since it uses less digits than its factorization.

691345 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 180 (or 143 counting only the distinct ones).

The product of its digits is 3240, while the sum is 28.

The square root of 691345 is about 831.4715870070. The cubic root of 691345 is about 88.4229382268.

It can be divided in two parts, 691 and 345, that multiplied together give a triangular number (238395 = T₆₉₀).

The spelling of 691345 in words is "six hundred ninety-one thousand, three hundred forty-five".