821561625 has 24 divisors (see below), whose sum is σ = 1481003784. Its totient is φ = 438165600.

The previous prime is 821561623. The next prime is 821561647. The reversal of 821561625 is 526165128.

821561625 is a `hidden beast` number, since 8 + 2 + 15 + 616 + 25 = 666.

It can be written as a sum of positive squares in 4 ways, for example, as 16818201 + 804743424 = 4101^2 + 28368^2 .

It is not a de Polignac number, because 821561625 - 2¹ = 821561623 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 821561625.

It is not an unprimeable number, because it can be changed into a prime (821561621) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 364014 + ... + 366263.

It is an arithmetic number, because the mean of its divisors is an integer number (61708491).

Almost surely, 2^821561625 is an apocalyptic number.

It is an amenable number.

821561625 is a deficient number, since it is larger than the sum of its proper divisors (659442159).

821561625 is a wasteful number, since it uses less digits than its factorization.

821561625 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 730298 (or 730285 counting only the distinct ones).

The product of its digits is 28800, while the sum is 36.

The square root of 821561625 is about 28662.8963121315. The cubic root of 821561625 is about 936.5839585508.

The spelling of 821561625 in words is "eight hundred twenty-one million, five hundred sixty-one thousand, six hundred twenty-five".