691378 has 4 divisors (see below), whose sum is σ = 1037070. Its totient is φ = 345688.

The previous prime is 691363. The next prime is 691381. The reversal of 691378 is 873196.

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., 635209 + 56169 = 797^2 + 237^2 .

It is an unprimeable number.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 172843 + ... + 172846.

2⁶⁹¹³⁷⁸ is an apocalyptic number.

691378 is a deficient number, since it is larger than the sum of its proper divisors (345692).

691378 is a wasteful number, since it uses less digits than its factorization.

691378 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 345691.

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

The square root of 691378 is about 831.4914311044. The cubic root of 691378 is about 88.4243451031.

The spelling of 691378 in words is "six hundred ninety-one thousand, three hundred seventy-eight".