820607521 has 2 divisors, whose sum is σ = 820607522. Its totient is φ = 820607520.

The previous prime is 820607509. The next prime is 820607551. The reversal of 820607521 is 125706028.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 485717521 + 334890000 = 22039^2 + 18300^2 .

It is a cyclic number.

It is not a de Polignac number, because 820607521 - 2⁷ = 820607393 is a prime.

It is not a weakly prime, because it can be changed into another prime (820607551) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 410303760 + 410303761.

It is an arithmetic number, because the mean of its divisors is an integer number (410303761).

Almost surely, 2^820607521 is an apocalyptic number.

It is an amenable number.

820607521 is a deficient number, since it is larger than the sum of its proper divisors (1).

820607521 is an equidigital number, since it uses as much as digits as its factorization.

820607521 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 6720, while the sum is 31.

The square root of 820607521 is about 28646.2479393026. The cubic root of 820607521 is about 936.2212571546.

It can be divided in two parts, 820607 and 521, that added together give a palindrome (821128).

The spelling of 820607521 in words is "eight hundred twenty million, six hundred seven thousand, five hundred twenty-one".