1645981857 has 32 divisors (see below), whose sum is σ = 2646188160. Its totient is φ = 1005151680.

The previous prime is 1645981829. The next prime is 1645981873. The reversal of 1645981857 is 7581895461.

It is a happy number.

1645981857 is a `hidden beast` number, since 1 + 6 + 459 + 8 + 185 + 7 = 666.

It is not a de Polignac number, because 1645981857 - 2¹² = 1645977761 is a prime.

It is not an unprimeable number, because it can be changed into a prime (1645981817) 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 31 ways as a sum of consecutive naturals, for example, 28083 + ... + 63879.

It is an arithmetic number, because the mean of its divisors is an integer number (82693380).

Almost surely, 2^1645981857 is an apocalyptic number.

It is an amenable number.

1645981857 is a deficient number, since it is larger than the sum of its proper divisors (1000206303).

1645981857 is a wasteful number, since it uses less digits than its factorization.

1645981857 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 35950 (or 35944 counting only the distinct ones).

The product of its digits is 2419200, while the sum is 54.

The square root of 1645981857 is about 40570.7019535033. The cubic root of 1645981857 is about 1180.7057582575.

The spelling of 1645981857 in words is "one billion, six hundred forty-five million, nine hundred eighty-one thousand, eight hundred fifty-seven".