681455521 has 2 divisors, whose sum is σ = 681455522. Its totient is φ = 681455520.

The previous prime is 681455497. The next prime is 681455531. The reversal of 681455521 is 125554186.

681455521 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 606390625 + 75064896 = 24625^2 + 8664^2 .

It is a cyclic number.

It is not a de Polignac number, because 681455521 - 2⁹ = 681455009 is a prime.

It is not a weakly prime, because it can be changed into another prime (681455531) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 340727760 + 340727761.

It is an arithmetic number, because the mean of its divisors is an integer number (340727761).

Almost surely, 2^681455521 is an apocalyptic number.

It is an amenable number.

681455521 is a deficient number, since it is larger than the sum of its proper divisors (1).

681455521 is an equidigital number, since it uses as much as digits as its factorization.

681455521 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 48000, while the sum is 37.

The square root of 681455521 is about 26104.7030437046. The cubic root of 681455521 is about 879.9929067094.

The spelling of 681455521 in words is "six hundred eighty-one million, four hundred fifty-five thousand, five hundred twenty-one".