1645945020 has 72 divisors (see below), whose sum is σ = 4999189104. Its totient is φ = 438348288.

The previous prime is 1645945003. The next prime is 1645945027. The reversal of 1645945020 is 205495461.

1645945020 is a `hidden beast` number, since 1 + 64 + 5 + 94 + 502 + 0 = 666.

It is a Harshad number since it is a multiple of its sum of digits (36).

It is a nialpdrome in base 15.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1645945027) 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 23 ways as a sum of consecutive naturals, for example, 143332 + ... + 154388.

It is an arithmetic number, because the mean of its divisors is an integer number (69433182).

Almost surely, 2^1645945020 is an apocalyptic number.

1645945020 is a gapful number since it is divisible by the number (10) formed by its first and last digit.

It is an amenable number.

1645945020 is an abundant number, since it is smaller than the sum of its proper divisors (3353244084).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

1645945020 is a wasteful number, since it uses less digits than its factorization.

1645945020 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 11899 (or 11894 counting only the distinct ones).

The product of its (nonzero) digits is 43200, while the sum is 36.

The square root of 1645945020 is about 40570.2479657199. The cubic root of 1645945020 is about 1180.6969501445.

The spelling of 1645945020 in words is "one billion, six hundred forty-five million, nine hundred forty-five thousand, twenty".