1645222621 has 16 divisors (see below), whose sum is σ = 1936263168. Its totient is φ = 1368547200.

The previous prime is 1645222619. The next prime is 1645222697. The reversal of 1645222621 is 1262225461.

It is not a de Polignac number, because 1645222621 - 2¹ = 1645222619 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1645222121) by changing a digit.

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 15 ways as a sum of consecutive naturals, for example, 39811 + ... + 69823.

It is an arithmetic number, because the mean of its divisors is an integer number (121016448).

Almost surely, 2^1645222621 is an apocalyptic number.

It is an amenable number.

1645222621 is a deficient number, since it is larger than the sum of its proper divisors (291040547).

1645222621 is a wasteful number, since it uses less digits than its factorization.

1645222621 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 30252.

The product of its digits is 11520, while the sum is 31.

The square root of 1645222621 is about 40561.3439249737. The cubic root of 1645222621 is about 1180.5241904028.

The spelling of 1645222621 in words is "one billion, six hundred forty-five million, two hundred twenty-two thousand, six hundred twenty-one".