1644660406 has 48 divisors (see below), whose sum is σ = 2678734800. Its totient is φ = 756941760.

The previous prime is 1644660403. The next prime is 1644660439. The reversal of 1644660406 is 6040664461.

It is a happy number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1644660403) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 4712320 + ... + 4712668.

It is an arithmetic number, because the mean of its divisors is an integer number (55806975).

Almost surely, 2^1644660406 is an apocalyptic number.

1644660406 is a deficient number, since it is larger than the sum of its proper divisors (1034074394).

1644660406 is a wasteful number, since it uses less digits than its factorization.

1644660406 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 557 (or 538 counting only the distinct ones).

The product of its (nonzero) digits is 82944, while the sum is 37.

The square root of 1644660406 is about 40554.4129041464. The cubic root of 1644660406 is about 1180.3897032285.

The spelling of 1644660406 in words is "one billion, six hundred forty-four million, six hundred sixty thousand, four hundred six".