1644136405 has 16 divisors (see below), whose sum is σ = 2079688320. Its totient is φ = 1244351808.

The previous prime is 1644136399. The next prime is 1644136409. The reversal of 1644136405 is 5046314461.

It is a cyclic number.

It is not a de Polignac number, because 1644136405 - 2²³ = 1635747797 is a prime.

It is a super-3 number, since 3×1644136405³ (a number of 29 digits) contains 333 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1644136409) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 58939 + ... + 82231.

It is an arithmetic number, because the mean of its divisors is an integer number (129980520).

Almost surely, 2^1644136405 is an apocalyptic number.

It is an amenable number.

1644136405 is a deficient number, since it is larger than the sum of its proper divisors (435551915).

1644136405 is a wasteful number, since it uses less digits than its factorization.

1644136405 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 24060.

The product of its (nonzero) digits is 34560, while the sum is 34.

The square root of 1644136405 is about 40547.9519211513. The cubic root of 1644136405 is about 1180.2643296086.

The spelling of 1644136405 in words is "one billion, six hundred forty-four million, one hundred thirty-six thousand, four hundred five".