840925721 has 2 divisors, whose sum is σ = 840925722. Its totient is φ = 840925720.

The previous prime is 840925717. The next prime is 840925783. The reversal of 840925721 is 127529048.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 668791321 + 172134400 = 25861^2 + 13120^2 .

It is a cyclic number.

It is not a de Polignac number, because 840925721 - 2² = 840925717 is a prime.

It is not a weakly prime, because it can be changed into another prime (840925021) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 420462860 + 420462861.

It is an arithmetic number, because the mean of its divisors is an integer number (420462861).

Almost surely, 2^840925721 is an apocalyptic number.

It is an amenable number.

840925721 is a deficient number, since it is larger than the sum of its proper divisors (1).

840925721 is an equidigital number, since it uses as much as digits as its factorization.

840925721 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 40320, while the sum is 38.

The square root of 840925721 is about 28998.7192993070. The cubic root of 840925721 is about 943.8852774170.

The spelling of 840925721 in words is "eight hundred forty million, nine hundred twenty-five thousand, seven hundred twenty-one".