1381831620921 has 20 divisors (see below), whose sum is σ = 2066560752564. Its totient is φ = 920175379200.

The previous prime is 1381831620899. The next prime is 1381831620977. The reversal of 1381831620921 is 1290261381831.

1381831620921 is a `hidden beast` number, since 1 + 3 + 8 + 18 + 3 + 1 + 620 + 9 + 2 + 1 = 666.

It can be written as a sum of positive squares in 2 ways, for example, as 286721695296 + 1095109925625 = 535464^2 + 1046475^2 .

It is not a de Polignac number, because 1381831620921 - 2¹¹ = 1381831618873 is a prime.

It is not an unprimeable number, because it can be changed into a prime (1381831620121) by changing a digit.

It is a polite number, since it can be written in 19 ways as a sum of consecutive naturals, for example, 9610620 + ... + 9753341.

Almost surely, 2^{1381831620921} is an apocalyptic number.

It is an amenable number.

1381831620921 is a deficient number, since it is larger than the sum of its proper divisors (684729131643).

1381831620921 is an equidigital number, since it uses as much as digits as its factorization.

1381831620921 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 19364854 (or 19364845 counting only the distinct ones).

The product of its (nonzero) digits is 124416, while the sum is 45.

The spelling of 1381831620921 in words is "one trillion, three hundred eighty-one billion, eight hundred thirty-one million, six hundred twenty thousand, nine hundred twenty-one".