61009406640 has 480 divisors, whose sum is σ = 256944804480. Its totient is φ = 12628721664.

The previous prime is 61009406611. The next prime is 61009406641. The reversal of 61009406640 is 4660490016.

61009406640 is a `hidden beast` number, since 6 + 1 + 0 + 0 + 9 + 4 + 0 + 6 + 640 = 666.

It is a Harshad number since it is a multiple of its sum of digits (36).

It is a junction number, because it is equal to n+sod(n) for n = 61009406595 and 61009406604.

It is not an unprimeable number, because it can be changed into a prime (61009406641) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 95 ways as a sum of consecutive naturals, for example, 3463776 + ... + 3481344.

It is an arithmetic number, because the mean of its divisors is an integer number (535301676).

Almost surely, 2^61009406640 is an apocalyptic number.

61009406640 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 61009406640, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (128472402240).

61009406640 is an abundant number, since it is smaller than the sum of its proper divisors (195935397840).

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

61009406640 is a wasteful number, since it uses less digits than its factorization.

61009406640 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 17661 (or 17652 counting only the distinct ones).

The product of its (nonzero) digits is 31104, while the sum is 36.

Adding to 61009406640 its reverse (4660490016), we get a palindrome (65669896656).

The spelling of 61009406640 in words is "sixty-one billion, nine million, four hundred six thousand, six hundred forty".