856440225 has 27 divisors (see below), whose sum is σ = 1534766259. Its totient is φ = 456534000.

The previous prime is 856440203. The next prime is 856440241. The reversal of 856440225 is 522044658.

It is a happy number.

The square root of 856440225 is 29265.

It is a perfect power (a square), and thus also a powerful number.

856440225 is a `hidden beast` number, since 8 + 5 + 644 + 0 + 2 + 2 + 5 = 666.

It can be written as a sum of positive squares in only one way, i.e., 308318481 + 548121744 = 17559^2 + 23412^2 .

It is not a de Polignac number, because 856440225 - 2⁹ = 856439713 is a prime.

It is a Curzon number.

It is a self number, because there is not a number n which added to its sum of digits gives 856440225.

It is an unprimeable number.

It is a polite number, since it can be written in 26 ways as a sum of consecutive naturals, for example, 438000 + ... + 439950.

Almost surely, 2^856440225 is an apocalyptic number.

856440225 is the 29265-th square number.

856440225 is the 14633-rd centered octagonal number.

It is an amenable number.

856440225 is a deficient number, since it is larger than the sum of its proper divisors (678326034).

856440225 is an equidigital number, since it uses as much as digits as its factorization.

856440225 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3918 (or 1959 counting only the distinct ones).

The product of its (nonzero) digits is 76800, while the sum is 36.

The cubic root of 856440225 is about 949.6546205257.

Multiplying 856440225 by its sum of digits (36), we get a square (30831848100 = 175590²).

The spelling of 856440225 in words is "eight hundred fifty-six million, four hundred forty thousand, two hundred twenty-five".