61691 has 6 divisors (see below), whose sum is σ = 71820. Its totient is φ = 52836.

The previous prime is 61687. The next prime is 61703. The reversal of 61691 is 19616.

It is not a de Polignac number, because 61691 - 2² = 61687 is a prime.

It is not an unprimeable number, because it can be changed into a prime (61631) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 581 + ... + 678.

It is an arithmetic number, because the mean of its divisors is an integer number (11970).

2⁶¹⁶⁹¹ is an apocalyptic number.

61691 is a deficient number, since it is larger than the sum of its proper divisors (10129).

61691 is a wasteful number, since it uses less digits than its factorization.

61691 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1273 (or 1266 counting only the distinct ones).

The product of its digits is 324, while the sum is 23.

The square root of 61691 is about 248.3767299889. The cubic root of 61691 is about 39.5130544898.

It can be divided in two parts, 616 and 91, that added together give a palindrome (707).

The spelling of 61691 in words is "sixty-one thousand, six hundred ninety-one".