821211225 has 12 divisors (see below), whose sum is σ = 1357736016. Its totient is φ = 437979280.

The previous prime is 821211199. The next prime is 821211227. The reversal of 821211225 is 522112128.

It is not a de Polignac number, because 821211225 - 2⁸ = 821210969 is a prime.

It is a Curzon number.

It is a junction number, because it is equal to n+sod(n) for n = 821211195 and 821211204.

It is not an unprimeable number, because it can be changed into a prime (821211227) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 5474667 + ... + 5474816.

It is an arithmetic number, because the mean of its divisors is an integer number (113144668).

Almost surely, 2^821211225 is an apocalyptic number.

It is an amenable number.

821211225 is a deficient number, since it is larger than the sum of its proper divisors (536524791).

821211225 is a wasteful number, since it uses less digits than its factorization.

821211225 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 10949496 (or 10949491 counting only the distinct ones).

The product of its digits is 640, while the sum is 24.

The square root of 821211225 is about 28656.7832284086. The cubic root of 821211225 is about 936.4507870894.

The spelling of 821211225 in words is "eight hundred twenty-one million, two hundred eleven thousand, two hundred twenty-five".