820619521 has 2 divisors, whose sum is σ = 820619522. Its totient is φ = 820619520.

The previous prime is 820619497. The next prime is 820619573. The reversal of 820619521 is 125916028.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 574129521 + 246490000 = 23961^2 + 15700^2 .

It is a cyclic number.

It is not a de Polignac number, because 820619521 - 2⁵ = 820619489 is a prime.

It is not a weakly prime, because it can be changed into another prime (820616521) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 410309760 + 410309761.

It is an arithmetic number, because the mean of its divisors is an integer number (410309761).

Almost surely, 2^820619521 is an apocalyptic number.

It is an amenable number.

820619521 is a deficient number, since it is larger than the sum of its proper divisors (1).

820619521 is an equidigital number, since it uses as much as digits as its factorization.

820619521 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 8640, while the sum is 34.

The square root of 820619521 is about 28646.4573900509. The cubic root of 820619521 is about 936.2258206843.

The spelling of 820619521 in words is "eight hundred twenty million, six hundred nineteen thousand, five hundred twenty-one".