393971644 has 18 divisors (see below), whose sum is σ = 757826552. Its totient is φ = 179077800.

The previous prime is 393971639. The next prime is 393971681. The reversal of 393971644 is 446179393.

It is a junction number, because it is equal to n+sod(n) for n = 393971594 and 393971603.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 406512 + ... + 407479.

Almost surely, 2^393971644 is an apocalyptic number.

It is an amenable number.

393971644 is a deficient number, since it is larger than the sum of its proper divisors (363854908).

393971644 is a wasteful number, since it uses less digits than its factorization.

393971644 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 814017 (or 814004 counting only the distinct ones).

The product of its digits is 489888, while the sum is 46.

The square root of 393971644 is about 19848.7189511061. The cubic root of 393971644 is about 733.0861055507.

It can be divided in two parts, 39397 and 1644, that added together give a triangular number (41041 = T₂₈₆).

The spelling of 393971644 in words is "three hundred ninety-three million, nine hundred seventy-one thousand, six hundred forty-four".