1812742781 has 4 divisors (see below), whose sum is σ = 1812862464. Its totient is φ = 1812623100.

The previous prime is 1812742753. The next prime is 1812742783. The reversal of 1812742781 is 1872472181.

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: 1872472181 = 9479 ⋅197539.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-1812742781 is a prime.

It is a super-2 number, since 2×1812742781² = 6572072780135227922, which contains 22 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 (1812742783) 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, 33155 + ... + 68736.

It is an arithmetic number, because the mean of its divisors is an integer number (453215616).

Almost surely, 2^1812742781 is an apocalyptic number.

It is an amenable number.

1812742781 is a deficient number, since it is larger than the sum of its proper divisors (119683).

1812742781 is a wasteful number, since it uses less digits than its factorization.

1812742781 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 119682.

The product of its digits is 50176, while the sum is 41.

The square root of 1812742781 is about 42576.3171375825. The cubic root of 1812742781 is about 1219.3041765820.

The spelling of 1812742781 in words is "one billion, eight hundred twelve million, seven hundred forty-two thousand, seven hundred eighty-one".