865724381 has 4 divisors (see below), whose sum is σ = 868177212. Its totient is φ = 863271552.

The previous prime is 865724359. The next prime is 865724477. The reversal of 865724381 is 183427568.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 704053156 + 161671225 = 26534^2 + 12715^2 .

It is a cyclic number.

It is not a de Polignac number, because 865724381 - 2²² = 861530077 is a prime.

It is a super-2 number, since 2×865724381² = 1498957407715666322, 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 (865724311) 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, 1225886 + ... + 1226591.

It is an arithmetic number, because the mean of its divisors is an integer number (217044303).

Almost surely, 2^865724381 is an apocalyptic number.

It is an amenable number.

865724381 is a deficient number, since it is larger than the sum of its proper divisors (2452831).

865724381 is a wasteful number, since it uses less digits than its factorization.

865724381 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2452830.

The product of its digits is 322560, while the sum is 44.

The square root of 865724381 is about 29423.1946090155. The cubic root of 865724381 is about 953.0738407169.

The spelling of 865724381 in words is "eight hundred sixty-five million, seven hundred twenty-four thousand, three hundred eighty-one".