13406781 has 4 divisors (see below), whose sum is σ = 17875712. Its totient is φ = 8937852.

The previous prime is 13406777. The next prime is 13406803. The reversal of 13406781 is 18760431.

It is a happy number.

13406781 is digitally balanced in base 2 and base 3, because in such bases 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 a Blum integer, because the two primes are equal to 3 mod 4, and also an emirpimes, since its reverse is a distinct semiprime: 18760431 = 3 ⋅6253477.

It is not a de Polignac number, because 13406781 - 2² = 13406777 is a prime.

It is a super-2 number, since 2×13406781² = 359483553563922, 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 (13406711) 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, 2234461 + ... + 2234466.

It is an arithmetic number, because the mean of its divisors is an integer number (4468928).

Almost surely, 2^13406781 is an apocalyptic number.

It is an amenable number.

13406781 is a deficient number, since it is larger than the sum of its proper divisors (4468931).

13406781 is an equidigital number, since it uses as much as digits as its factorization.

13406781 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4468930.

The product of its (nonzero) digits is 4032, while the sum is 30.

The square root of 13406781 is about 3661.5271404156. The cubic root of 13406781 is about 237.5608324320.

The spelling of 13406781 in words is "thirteen million, four hundred six thousand, seven hundred eighty-one".