61638018 has 48 divisors (see below), whose sum is σ = 135185760. Its totient is φ = 18724992.

The previous prime is 61638007. The next prime is 61638019. The reversal of 61638018 is 81083616.

It is a Curzon number.

It is a self number, because there is not a number n which added to its sum of digits gives 61638018.

It is not an unprimeable number, because it can be changed into a prime (61638019) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 89905 + ... + 90587.

It is an arithmetic number, because the mean of its divisors is an integer number (2816370).

Almost surely, 2^61638018 is an apocalyptic number.

It is a practical number, because each smaller number is the sum of distinct divisors of 61638018, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (67592880).

61638018 is an abundant number, since it is smaller than the sum of its proper divisors (73547742).

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

61638018 is a wasteful number, since it uses less digits than its factorization.

61638018 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 803 (or 790 counting only the distinct ones).

The product of its (nonzero) digits is 6912, while the sum is 33.

The square root of 61638018 is about 7850.9883454251. The cubic root of 61638018 is about 395.0173960186.

The spelling of 61638018 in words is "sixty-one million, six hundred thirty-eight thousand, eighteen".