981979781 has 4 divisors (see below), whose sum is σ = 985800972. Its totient is φ = 978158592.

The previous prime is 981979753. The next prime is 981979787. The reversal of 981979781 is 187979189.

981979781 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 187979189 = 29 ⋅6482041.

It can be written as a sum of positive squares in 2 ways, for example, as 971319556 + 10660225 = 31166^2 + 3265^2 .

It is a cyclic number.

It is not a de Polignac number, because 981979781 - 2¹⁸ = 981717637 is a prime.

It is a super-2 number, since 2×981979781² = 1928568580585615922, which contains 22 as substring.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 981979781.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (981979787) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 1910210 + ... + 1910723.

It is an arithmetic number, because the mean of its divisors is an integer number (246450243).

Almost surely, 2^981979781 is an apocalyptic number.

It is an amenable number.

981979781 is a deficient number, since it is larger than the sum of its proper divisors (3821191).

981979781 is a wasteful number, since it uses less digits than its factorization.

981979781 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3821190.

The product of its digits is 2286144, while the sum is 59.

The square root of 981979781 is about 31336.5566232156. The cubic root of 981979781 is about 993.9568137998.

The spelling of 981979781 in words is "nine hundred eighty-one million, nine hundred seventy-nine thousand, seven hundred eighty-one".