12612781 has 4 divisors (see below), whose sum is σ = 12850812. Its totient is φ = 12374752.

The previous prime is 12612773. The next prime is 12612791. The reversal of 12612781 is 18721621.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 18721621 = 433 ⋅43237.

It can be written as a sum of positive squares in 2 ways, for example, as 10666756 + 1946025 = 3266^2 + 1395^2 .

It is a cyclic number.

It is not a de Polignac number, because 12612781 - 2³ = 12612773 is a prime.

It is a super-2 number, since 2×12612781² = 318164489107922, 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 (12612791) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 118936 + ... + 119041.

It is an arithmetic number, because the mean of its divisors is an integer number (3212703).

Almost surely, 2^12612781 is an apocalyptic number.

It is an amenable number.

12612781 is a deficient number, since it is larger than the sum of its proper divisors (238031).

12612781 is an equidigital number, since it uses as much as digits as its factorization.

12612781 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 238030.

The product of its digits is 1344, while the sum is 28.

The square root of 12612781 is about 3551.4477329675. The cubic root of 12612781 is about 232.7753303512.

Subtracting from 12612781 its sum of digits (28), we obtain a triangular number (12612753 = T₅₀₂₂).

The spelling of 12612781 in words is "twelve million, six hundred twelve thousand, seven hundred eighty-one".