1644779436 has 12 divisors (see below), whose sum is σ = 3837818712. Its totient is φ = 548259808.

The previous prime is 1644779419. The next prime is 1644779471. The reversal of 1644779436 is 6349774461.

It is a tau number, because it is divible by the number of its divisors (12).

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 68532465 + ... + 68532488.

It is an arithmetic number, because the mean of its divisors is an integer number (319818226).

Almost surely, 2^1644779436 is an apocalyptic number.

It is an amenable number.

1644779436 is an abundant number, since it is smaller than the sum of its proper divisors (2193039276).

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

1644779436 is a wasteful number, since it uses less digits than its factorization.

1644779436 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 137064960 (or 137064958 counting only the distinct ones).

The product of its digits is 3048192, while the sum is 51.

The square root of 1644779436 is about 40555.8804120931. The cubic root of 1644779436 is about 1180.4181788936.

The spelling of 1644779436 in words is "one billion, six hundred forty-four million, seven hundred seventy-nine thousand, four hundred thirty-six".