61640040 has 192 divisors, whose sum is σ = 234912960. Its totient is φ = 12794880.

The previous prime is 61640017. The next prime is 61640053. The reversal of 61640040 is 4004616.

61640040 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a Harshad number since it is a multiple of its sum of digits (21).

It is a junction number, because it is equal to n+sod(n) for n = 61639989 and 61640016.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 64204 + ... + 65156.

It is an arithmetic number, because the mean of its divisors is an integer number (1223505).

Almost surely, 2^61640040 is an apocalyptic number.

61640040 is a gapful number since it is divisible by the number (60) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 61640040, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (117456480).

61640040 is an abundant number, since it is smaller than the sum of its proper divisors (173272920).

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

61640040 is a wasteful number, since it uses less digits than its factorization.

61640040 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 992 (or 981 counting only the distinct ones).

The product of its (nonzero) digits is 576, while the sum is 21.

The square root of 61640040 is about 7851.1171179648. The cubic root of 61640040 is about 395.0217154114.

Adding to 61640040 its reverse (4004616), we get a palindrome (65644656).

The spelling of 61640040 in words is "sixty-one million, six hundred forty thousand, forty".