863721 has 12 divisors (see below), whose sum is σ = 1313520. Its totient is φ = 545400.

The previous prime is 863711. The next prime is 863729. The reversal of 863721 is 127368.

863721 is a `hidden beast` number, since 8 + 637 + 21 = 666.

It is not a de Polignac number, because 863721 - 2⁵ = 863689 is a prime.

It is a Smith number, since the sum of its digits (27) coincides with the sum of the digits of its prime factors.

863721 is a lucky number.

It is not an unprimeable number, because it can be changed into a prime (863729) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 2355 + ... + 2696.

It is an arithmetic number, because the mean of its divisors is an integer number (109460).

2⁸⁶³⁷²¹ is an apocalyptic number.

It is an amenable number.

863721 is a deficient number, since it is larger than the sum of its proper divisors (449799).

863721 is a wasteful number, since it uses less digits than its factorization.

863721 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 5076 (or 5073 counting only the distinct ones).

The product of its digits is 2016, while the sum is 27.

The square root of 863721 is about 929.3659128675. The cubic root of 863721 is about 95.2338100493.

The spelling of 863721 in words is "eight hundred sixty-three thousand, seven hundred twenty-one".