840721841 has 4 divisors (see below), whose sum is σ = 840843300. Its totient is φ = 840600384.

The previous prime is 840721837. The next prime is 840721873. The reversal of 840721841 is 148127048.

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 703363441 + 137358400 = 26521^2 + 11720^2 .

It is a cyclic number.

It is not a de Polignac number, because 840721841 - 2² = 840721837 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (840721811) 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, 49676 + ... + 64413.

It is an arithmetic number, because the mean of its divisors is an integer number (210210825).

Almost surely, 2^840721841 is an apocalyptic number.

It is an amenable number.

840721841 is a deficient number, since it is larger than the sum of its proper divisors (121459).

840721841 is a wasteful number, since it uses less digits than its factorization.

840721841 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 121458.

The product of its (nonzero) digits is 14336, while the sum is 35.

The square root of 840721841 is about 28995.2037585529. The cubic root of 840721841 is about 943.8089905029.

Adding to 840721841 its reverse (148127048), we get a palindrome (988848889).

The spelling of 840721841 in words is "eight hundred forty million, seven hundred twenty-one thousand, eight hundred forty-one".