1981396879642 has 64 divisors (see below), whose sum is σ = 3245486717088. Its totient is φ = 903536640000.

The previous prime is 1981396879639. The next prime is 1981396879667. The reversal of 1981396879642 is 2469786931891.

It is a Cunningham number, because it is equal to 1407621²+1.

It can be written as a sum of positive squares in 16 ways, for example, as 133050587121 + 1848346292521 = 364761^2 + 1359539^2 .

It is a super-3 number, since 3×1981396879642³ (a number of 38 digits) contains 333 as substring.

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 31 ways as a sum of consecutive naturals, for example, 289632142 + ... + 289638982.

Almost surely, 2^{1981396879642} is an apocalyptic number.

1981396879642 is a deficient number, since it is larger than the sum of its proper divisors (1264089837446).

1981396879642 is a wasteful number, since it uses less digits than its factorization.

1981396879642 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 8275.

The product of its digits is 282175488, while the sum is 73.

The spelling of 1981396879642 in words is "one trillion, nine hundred eighty-one billion, three hundred ninety-six million, eight hundred seventy-nine thousand, six hundred forty-two".