1831721637956 has 18 divisors (see below), whose sum is σ = 3728861906238. Its totient is φ = 785023559040.

The previous prime is 1831721637923. The next prime is 1831721637971. The reversal of 1831721637956 is 6597361271381.

It is a happy number.

It can be written as a sum of positive squares in only one way, i.e., 1782668247556 + 49053390400 = 1335166^2 + 221480^2 .

It is a junction number, because it is equal to n+sod(n) for n = 1831721637895 and 1831721637904.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 4672759085 + ... + 4672759476.

It is an arithmetic number, because the mean of its divisors is an integer number (207158994791).

Almost surely, 2^{1831721637956} is an apocalyptic number.

It is an amenable number.

1831721637956 is an abundant number, since it is smaller than the sum of its proper divisors (1897140268282).

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

1831721637956 is a wasteful number, since it uses less digits than its factorization.

1831721637956 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 9345518579 (or 9345518570 counting only the distinct ones).

The product of its digits is 11430720, while the sum is 59.

The spelling of 1831721637956 in words is "one trillion, eight hundred thirty-one billion, seven hundred twenty-one million, six hundred thirty-seven thousand, nine hundred fifty-six".