821506225 has 12 divisors (see below), whose sum is σ = 1028756700. Its totient is φ = 650696000.

The previous prime is 821506187. The next prime is 821506261. The reversal of 821506225 is 522605128.

821506225 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It can be written as a sum of positive squares in 6 ways, for example, as 339889 + 821166336 = 583^2 + 28656^2 .

It is a de Polignac number, because none of the positive numbers 2^k-821506225 is a prime.

It is an unprimeable number.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 160150 + ... + 165199.

It is an arithmetic number, because the mean of its divisors is an integer number (85729725).

Almost surely, 2^821506225 is an apocalyptic number.

It is an amenable number.

821506225 is a deficient number, since it is larger than the sum of its proper divisors (207250475).

821506225 is a wasteful number, since it uses less digits than its factorization.

821506225 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 325460 (or 325455 counting only the distinct ones).

The product of its (nonzero) digits is 9600, while the sum is 31.

The square root of 821506225 is about 28661.9298896637. The cubic root of 821506225 is about 936.5629059943.

The spelling of 821506225 in words is "eight hundred twenty-one million, five hundred six thousand, two hundred twenty-five".