61681 has 2 divisors, whose sum is σ = 61682. Its totient is φ = 61680.

The previous prime is 61673. The next prime is 61687. The reversal of 61681 is 18616.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 58081 + 3600 = 241^2 + 60^2 .

It is a cyclic number.

It is not a de Polignac number, because 61681 - 2³ = 61673 is a prime.

It is a super-2 number, since 2×61681² = 7609091522, which contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (61687) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 30840 + 30841.

It is an arithmetic number, because the mean of its divisors is an integer number (30841).

2⁶¹⁶⁸¹ is an apocalyptic number.

It is an amenable number.

61681 is a deficient number, since it is larger than the sum of its proper divisors (1).

61681 is an equidigital number, since it uses as much as digits as its factorization.

61681 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 288, while the sum is 22.

The square root of 61681 is about 248.3565984628. The cubic root of 61681 is about 39.5109193761.

The spelling of 61681 in words is "sixty-one thousand, six hundred eighty-one".