1781271042109 has 4 divisors (see below), whose sum is σ = 1918291891516. Its totient is φ = 1644250192704.

The previous prime is 1781271042097. The next prime is 1781271042121. The reversal of 1781271042109 is 9012401721871.

It is a semiprime because it is the product of two primes.

It is an interprime number because it is at equal distance from previous prime (1781271042097) and next prime (1781271042121).

It can be written as a sum of positive squares in 2 ways, for example, as 114499670884 + 1666771371225 = 338378^2 + 1291035^2 .

It is a cyclic number.

It is not a de Polignac number, because 1781271042109 - 2⁵ = 1781271042077 is a prime.

It is a super-3 number, since 3×1781271042109³ (a number of 38 digits) contains 333 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1781271043109) 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, 68510424684 + ... + 68510424709.

It is an arithmetic number, because the mean of its divisors is an integer number (479572972879).

Almost surely, 2^{1781271042109} is an apocalyptic number.

It is an amenable number.

1781271042109 is a deficient number, since it is larger than the sum of its proper divisors (137020849407).

1781271042109 is a wasteful number, since it uses less digits than its factorization.

1781271042109 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 137020849406.

The product of its (nonzero) digits is 56448, while the sum is 43.

The spelling of 1781271042109 in words is "one trillion, seven hundred eighty-one billion, two hundred seventy-one million, forty-two thousand, one hundred nine".