63691 has 2 divisors, whose sum is σ = 63692. Its totient is φ = 63690.

The previous prime is 63689. The next prime is 63697. The reversal of 63691 is 19636.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 63691 - 2¹ = 63689 is a prime.

Together with 63689, it forms a pair of twin primes.

It is not a weakly prime, because it can be changed into another prime (63697) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 31845 + 31846.

It is an arithmetic number, because the mean of its divisors is an integer number (31846).

2⁶³⁶⁹¹ is an apocalyptic number.

63691 is a deficient number, since it is larger than the sum of its proper divisors (1).

63691 is an equidigital number, since it uses as much as digits as its factorization.

63691 is an evil number, because the sum of its binary digits is even.

The product of its digits is 972, while the sum is 25.

The square root of 63691 is about 252.3707590035. The cubic root of 63691 is about 39.9355211177.

It can be divided in two parts, 636 and 91, that added together give a palindrome (727).

The spelling of 63691 in words is "sixty-three thousand, six hundred ninety-one".