840218721 has 16 divisors (see below), whose sum is σ = 1131076800. Its totient is φ = 554773248.

The previous prime is 840218713. The next prime is 840218723. The reversal of 840218721 is 127812048.

It is a happy number.

It is not a de Polignac number, because 840218721 - 2³ = 840218713 is a prime.

It is not an unprimeable number, because it can be changed into a prime (840218723) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 188365 + ... + 192773.

It is an arithmetic number, because the mean of its divisors is an integer number (70692300).

Almost surely, 2^840218721 is an apocalyptic number.

It is an amenable number.

840218721 is a deficient number, since it is larger than the sum of its proper divisors (290858079).

840218721 is a wasteful number, since it uses less digits than its factorization.

840218721 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 5008.

The product of its (nonzero) digits is 7168, while the sum is 33.

The square root of 840218721 is about 28986.5265425163. The cubic root of 840218721 is about 943.6206825077.

The spelling of 840218721 in words is "eight hundred forty million, two hundred eighteen thousand, seven hundred twenty-one".