2381781 has 4 divisors (see below), whose sum is σ = 3175712. Its totient is φ = 1587852.

The previous prime is 2381777. The next prime is 2381789. The reversal of 2381781 is 1871832.

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 not a de Polignac number, because 2381781 - 2² = 2381777 is a prime.

It is a super-2 number, since 2×2381781² = 11345761463922, which contains 22 as substring.

It is a D-number.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (2381789) 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, 396961 + ... + 396966.

It is an arithmetic number, because the mean of its divisors is an integer number (793928).

2^2381781 is an apocalyptic number.

It is an amenable number.

2381781 is a deficient number, since it is larger than the sum of its proper divisors (793931).

2381781 is an equidigital number, since it uses as much as digits as its factorization.

2381781 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 793930.

The product of its digits is 2688, while the sum is 30.

The square root of 2381781 is about 1543.3019795231. The cubic root of 2381781 is about 133.5469402468.

The spelling of 2381781 in words is "two million, three hundred eighty-one thousand, seven hundred eighty-one".