61840 has 20 divisors (see below), whose sum is σ = 143964. Its totient is φ = 24704.

The previous prime is 61837. The next prime is 61843. The reversal of 61840 is 4816.

It is an interprime number because it is at equal distance from previous prime (61837) and next prime (61843).

It can be written as a sum of positive squares in 2 ways, for example, as 11664 + 50176 = 108^2 + 224^2 .

It is a tau number, because it is divible by the number of its divisors (20).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (61843) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (7) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 307 + ... + 466.

2⁶¹⁸⁴⁰ is an apocalyptic number.

It is an amenable number.

61840 is an abundant number, since it is smaller than the sum of its proper divisors (82124).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

It is a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (71982).

61840 is a wasteful number, since it uses less digits than its factorization.

61840 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 786 (or 780 counting only the distinct ones).

The product of its (nonzero) digits is 192, while the sum is 19.

The square root of 61840 is about 248.6764966779. The cubic root of 61840 is about 39.5448403881.

The spelling of 61840 in words is "sixty-one thousand, eight hundred forty".