1645221245 has 8 divisors (see below), whose sum is σ = 1977468984. Its totient is φ = 1314041344.

The previous prime is 1645221173. The next prime is 1645221287. The reversal of 1645221245 is 5421225461.

It can be written as a sum of positive squares in 4 ways, for example, as 98922916 + 1546298329 = 9946^2 + 39323^2 .

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 1645221245 - 2¹⁰ = 1645220221 is a prime.

It is a Duffinian number.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 263564 + ... + 269733.

It is an arithmetic number, because the mean of its divisors is an integer number (247183623).

Almost surely, 2^1645221245 is an apocalyptic number.

It is an amenable number.

1645221245 is a deficient number, since it is larger than the sum of its proper divisors (332247739).

1645221245 is an equidigital number, since it uses as much as digits as its factorization.

1645221245 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 533919.

The product of its digits is 19200, while the sum is 32.

The square root of 1645221245 is about 40561.3269630075. The cubic root of 1645221245 is about 1180.5238612879.

The spelling of 1645221245 in words is "one billion, six hundred forty-five million, two hundred twenty-one thousand, two hundred forty-five".