1645221225 has 24 divisors (see below), whose sum is σ = 2723372320. Its totient is φ = 876395520.

The previous prime is 1645221173. The next prime is 1645221287. The reversal of 1645221225 is 5221225461.

It is not a de Polignac number, because 1645221225 - 2⁶ = 1645221161 is a prime.

It is a Curzon number.

It is a junction number, because it is equal to n+sod(n) for n = 1645221192 and 1645221201.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 51657 + ... + 77193.

Almost surely, 2^1645221225 is an apocalyptic number.

1645221225 is a gapful number since it is divisible by the number (15) formed by its first and last digit.

It is an amenable number.

1645221225 is a deficient number, since it is larger than the sum of its proper divisors (1078151095).

1645221225 is a wasteful number, since it uses less digits than its factorization.

1645221225 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 26409 (or 26404 counting only the distinct ones).

The product of its digits is 9600, while the sum is 30.

The square root of 1645221225 is about 40561.3267164673. The cubic root of 1645221225 is about 1180.5238565042.

Adding to 1645221225 its reverse (5221225461), we get a palindrome (6866446686).

The spelling of 1645221225 in words is "one billion, six hundred forty-five million, two hundred twenty-one thousand, two hundred twenty-five".