61891 has 4 divisors (see below), whose sum is σ = 63000. Its totient is φ = 60784.

The previous prime is 61879. The next prime is 61909. The reversal of 61891 is 19816.

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

It is a cyclic number.

It is not a de Polignac number, because 61891 - 2⁹ = 61379 is a prime.

It is an Ulam number.

It is a Duffinian number.

It is a plaindrome in base 13.

It is a zygodrome in base 2.

It is not an unprimeable number, because it can be changed into a prime (61861) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 466 + ... + 583.

It is an arithmetic number, because the mean of its divisors is an integer number (15750).

2⁶¹⁸⁹¹ is an apocalyptic number.

61891 is a deficient number, since it is larger than the sum of its proper divisors (1109).

61891 is a wasteful number, since it uses less digits than its factorization.

61891 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1108.

The product of its digits is 432, while the sum is 25.

The square root of 61891 is about 248.7790184079. The cubic root of 61891 is about 39.5557083953. Note that the first 3 decimals are identical.

Adding to 61891 its sum of digits (25), we get a palindrome (61916).

The spelling of 61891 in words is "sixty-one thousand, eight hundred ninety-one".