61783731906 has 128 divisors (see below), whose sum is σ = 139345920000. Its totient is φ = 18131662080.

The previous prime is 61783731901. The next prime is 61783731913. The reversal of 61783731906 is 60913738716.

61783731906 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is not an unprimeable number, because it can be changed into a prime (61783731901) by changing a digit.

It is a polite number, since it can be written in 63 ways as a sum of consecutive naturals, for example, 123814845 + ... + 123815343.

It is an arithmetic number, because the mean of its divisors is an integer number (1088640000).

Almost surely, 2^61783731906 is an apocalyptic number.

It is a practical number, because each smaller number is the sum of distinct divisors of 61783731906, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (69672960000).

61783731906 is an abundant number, since it is smaller than the sum of its proper divisors (77562188094).

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

61783731906 is a wasteful number, since it uses less digits than its factorization.

61783731906 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1104.

The product of its (nonzero) digits is 1143072, while the sum is 51.

The spelling of 61783731906 in words is "sixty-one billion, seven hundred eighty-three million, seven hundred thirty-one thousand, nine hundred six".