691636 has 18 divisors (see below), whose sum is σ = 1331330. Its totient is φ = 314160.

The previous prime is 691631. The next prime is 691637. The reversal of 691636 is 636196.

691636 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It can be written as a sum of positive squares in only one way, i.e., 435600 + 256036 = 660^2 + 506^2 .

It is a junction number, because it is equal to n+sod(n) for n = 691598 and 691607.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (691631) by changing a digit.

691636 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 in 5 ways as a sum of consecutive naturals, for example, 231 + ... + 1198.

2⁶⁹¹⁶³⁶ is an apocalyptic number.

It is an amenable number.

691636 is a deficient number, since it is larger than the sum of its proper divisors (639694).

691636 is a wasteful number, since it uses less digits than its factorization.

691636 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1455 (or 1442 counting only the distinct ones).

The product of its digits is 5832, while the sum is 31.

The square root of 691636 is about 831.6465595432. The cubic root of 691636 is about 88.4353427743.

It can be divided in two parts, 69163 and 6, that added together give a square (69169 = 263²).

The spelling of 691636 in words is "six hundred ninety-one thousand, six hundred thirty-six".