1981386709 has 4 divisors (see below), whose sum is σ = 2085670240. Its totient is φ = 1877103180.

The previous prime is 1981386677. The next prime is 1981386713. The reversal of 1981386709 is 9076831891.

It is a happy number.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4, and also an emirpimes, since its reverse is a distinct semiprime: 9076831891 = 401 ⋅22635491.

It is a cyclic number.

It is not a de Polignac number, because 1981386709 - 2⁵ = 1981386677 is a prime.

It is a super-3 number, since 3×1981386709³ (a number of 29 digits) contains 333 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1981386769) 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, 52141737 + ... + 52141774.

It is an arithmetic number, because the mean of its divisors is an integer number (521417560).

Almost surely, 2^1981386709 is an apocalyptic number.

1981386709 is a gapful number since it is divisible by the number (19) formed by its first and last digit.

It is an amenable number.

1981386709 is a deficient number, since it is larger than the sum of its proper divisors (104283531).

1981386709 is a wasteful number, since it uses less digits than its factorization.

1981386709 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 104283530.

The product of its (nonzero) digits is 653184, while the sum is 52.

The square root of 1981386709 is about 44512.7701789048. The cubic root of 1981386709 is about 1256.0003154708. Note that the first 3 decimals are identical.

The spelling of 1981386709 in words is "one billion, nine hundred eighty-one million, three hundred eighty-six thousand, seven hundred nine".