1645609923 has 6 divisors (see below), whose sum is σ = 2376992124. Its totient is φ = 1097073276.

The previous prime is 1645609913. The next prime is 1645609961. The reversal of 1645609923 is 3299065461.

1645609923 is a `hidden beast` number, since 1 + 64 + 560 + 9 + 9 + 23 = 666.

It is not a de Polignac number, because 1645609923 - 2¹⁸ = 1645347779 is a prime.

It is not an unprimeable number, because it can be changed into a prime (1645609913) by changing a digit.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 91422765 + ... + 91422782.

It is an arithmetic number, because the mean of its divisors is an integer number (396165354).

Almost surely, 2^1645609923 is an apocalyptic number.

1645609923 is a deficient number, since it is larger than the sum of its proper divisors (731382201).

1645609923 is a wasteful number, since it uses less digits than its factorization.

1645609923 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 182845553 (or 182845550 counting only the distinct ones).

The product of its (nonzero) digits is 349920, while the sum is 45.

The square root of 1645609923 is about 40566.1179187755. The cubic root of 1645609923 is about 1180.6168189020.

The spelling of 1645609923 in words is "one billion, six hundred forty-five million, six hundred nine thousand, nine hundred twenty-three".