1981396879641 has 9 divisors (see below), whose sum is σ = 2862023814741. Its totient is φ = 1320928437852.

The previous prime is 1981396879639. The next prime is 1981396879667. The reversal of 1981396879641 is 1469786931891.

The square root of 1981396879641 is 1407621.

It is a perfect power (a square), and thus also a powerful number.

1981396879641 is a `hidden beast` number, since 198 + 1 + 396 + 8 + 7 + 9 + 6 + 41 = 666.

It is a tau number, because it is divible by the number of its divisors (9).

It is not a de Polignac number, because 1981396879641 - 2¹ = 1981396879639 is a prime.

It is a super-3 number, since 3×1981396879641³ (a number of 38 digits) contains 333 as substring.

It is a self number, because there is not a number n which added to its sum of digits gives 1981396879641.

It is not an unprimeable number, because it can be changed into a prime (1981396879621) by changing a digit.

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 8 ways as a sum of consecutive naturals, for example, 3988260 + ... + 4457466.

Almost surely, 2^{1981396879641} is an apocalyptic number.

1981396879641 is the 1407621-st square number.

1981396879641 is the 703811-st centered octagonal number.

It is an amenable number.

1981396879641 is a deficient number, since it is larger than the sum of its proper divisors (880626935100).

1981396879641 is an frugal number, since it uses more digits than its factorization.

1981396879641 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 938420 (or 469210 counting only the distinct ones).

The product of its digits is 141087744, while the sum is 72.

The spelling of 1981396879641 in words is "one trillion, nine hundred eighty-one billion, three hundred ninety-six million, eight hundred seventy-nine thousand, six hundred forty-one".