61819811891816 has 96 divisors (see below), whose sum is σ = 134952319986120. Its totient is φ = 26437138759680.

The previous prime is 61819811891791. The next prime is 61819811891839.

It is a happy number.

61819811891816 is nontrivially palindromic in base 10.

61819811891816 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It can be written as a sum of positive squares in 4 ways, for example, as 54075580032100 + 7744231859716 = 7353610^2 + 2782846^2 .

It is a Harshad number since it is a multiple of its sum of digits (68).

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (23) of ones.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 43618520 + ... + 45013496.

Almost surely, 2^{61819811891816} 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 61819811891816, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (67476159993060).

61819811891816 is an abundant number, since it is smaller than the sum of its proper divisors (73132508094304).

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

61819811891816 is a wasteful number, since it uses less digits than its factorization.

61819811891816 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1397715 (or 1397700 counting only the distinct ones).

The product of its digits is 11943936, while the sum is 68.

The spelling of 61819811891816 in words is "sixty-one trillion, eight hundred nineteen billion, eight hundred eleven million, eight hundred ninety-one thousand, eight hundred sixteen".