13120781 has 4 divisors (see below), whose sum is σ = 13544064. Its totient is φ = 12697500.

The previous prime is 13120777. The next prime is 13120799. The reversal of 13120781 is 18702131.

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.

It is a cyclic number.

It is not a de Polignac number, because 13120781 - 2² = 13120777 is a prime.

It is a super-2 number, since 2×13120781² = 344309788099922, 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 (13120711) 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, 211595 + ... + 211656.

It is an arithmetic number, because the mean of its divisors is an integer number (3386016).

Almost surely, 2^13120781 is an apocalyptic number.

It is an amenable number.

13120781 is a deficient number, since it is larger than the sum of its proper divisors (423283).

13120781 is an equidigital number, since it uses as much as digits as its factorization.

13120781 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 423282.

The product of its (nonzero) digits is 336, while the sum is 23.

The square root of 13120781 is about 3622.2618624279. The cubic root of 13120781 is about 235.8594214489.

The spelling of 13120781 in words is "thirteen million, one hundred twenty thousand, seven hundred eighty-one".