691738 has 4 divisors (see below), whose sum is σ = 1037610. Its totient is φ = 345868.

The previous prime is 691729. The next prime is 691739. The reversal of 691738 is 837196.

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

It can be written as a sum of positive squares in only one way, i.e., 537289 + 154449 = 733^2 + 393^2 .

It is not an unprimeable number, because it can be changed into a prime (691739) by changing a digit.

691738 is an untouchable number, because it is not equal to the sum of proper divisors of any number.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 172933 + ... + 172936.

2⁶⁹¹⁷³⁸ is an apocalyptic number.

691738 is a deficient number, since it is larger than the sum of its proper divisors (345872).

691738 is a wasteful number, since it uses less digits than its factorization.

691738 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 345871.

The product of its digits is 9072, while the sum is 34.

The square root of 691738 is about 831.7078814103. The cubic root of 691738 is about 88.4396899365.

The spelling of 691738 in words is "six hundred ninety-one thousand, seven hundred thirty-eight".