613781 has 4 divisors (see below), whose sum is σ = 701472. Its totient is φ = 526092.

The previous prime is 613763. The next prime is 613807. The reversal of 613781 is 187316.

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 de Polignac number, because none of the positive numbers 2^k-613781 is a prime.

It is a super-2 number, since 2×613781² = 753454231922, which contains 22 as substring.

It is a Duffinian number.

It is a Curzon number.

It is a self number, because there is not a number n which added to its sum of digits gives 613781.

It is a congruent number.

It is an inconsummate number, since it does not exist a number n which divided by its sum of digits gives 613781.

It is not an unprimeable number, because it can be changed into a prime (613741) 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, 43835 + ... + 43848.

It is an arithmetic number, because the mean of its divisors is an integer number (175368).

2⁶¹³⁷⁸¹ is an apocalyptic number.

It is an amenable number.

613781 is a deficient number, since it is larger than the sum of its proper divisors (87691).

613781 is an equidigital number, since it uses as much as digits as its factorization.

613781 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 87690.

The product of its digits is 1008, while the sum is 26.

The square root of 613781 is about 783.4417655448. The cubic root of 613781 is about 84.9841262168.

The spelling of 613781 in words is "six hundred thirteen thousand, seven hundred eighty-one".