865397721 has 8 divisors (see below), whose sum is σ = 1159333024. Its totient is φ = 574197120.

The previous prime is 865397719. The next prime is 865397723. The reversal of 865397721 is 127793568.

It is an interprime number because it is at equal distance from previous prime (865397719) and next prime (865397723).

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 865397721 - 2¹ = 865397719 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (865397723) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 682936 + ... + 684201.

It is an arithmetic number, because the mean of its divisors is an integer number (144916628).

Almost surely, 2^865397721 is an apocalyptic number.

It is an amenable number.

865397721 is a deficient number, since it is larger than the sum of its proper divisors (293935303).

865397721 is a wasteful number, since it uses less digits than its factorization.

865397721 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1367351.

The product of its digits is 635040, while the sum is 48.

The square root of 865397721 is about 29417.6430225129. The cubic root of 865397721 is about 952.9539525733.

The spelling of 865397721 in words is "eight hundred sixty-five million, three hundred ninety-seven thousand, seven hundred twenty-one".