61540 has 24 divisors (see below), whose sum is σ = 137592. Its totient is φ = 23040.

The previous prime is 61519. The next prime is 61543. The reversal of 61540 is 4516.

It can be written as a sum of positive squares in 4 ways, for example, as 1024 + 60516 = 32^2 + 246^2 .

It is a plaindrome in base 15.

It is not an unprimeable number, because it can be changed into a prime (61543) 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 7 ways as a sum of consecutive naturals, for example, 250 + ... + 430.

It is an arithmetic number, because the mean of its divisors is an integer number (5733).

2⁶¹⁵⁴⁰ is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 61540, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (68796).

61540 is an abundant number, since it is smaller than the sum of its proper divisors (76052).

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

61540 is a wasteful number, since it uses less digits than its factorization.

61540 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 207 (or 205 counting only the distinct ones).

The product of its (nonzero) digits is 120, while the sum is 16.

The square root of 61540 is about 248.0725700274. The cubic root of 61540 is about 39.4807896761.

The spelling of 61540 in words is "sixty-one thousand, five hundred forty".