393971440 has 20 divisors (see below), whose sum is σ = 915983784. Its totient is φ = 157588544.

The previous prime is 393971429. The next prime is 393971443. The reversal of 393971440 is 44179393.

It is a happy number.

It is a tau number, because it is divible by the number of its divisors (20).

It is a Harshad number since it is a multiple of its sum of digits (40).

It is a junction number, because it is equal to n+sod(n) for n = 393971393 and 393971402.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (393971443) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 2462242 + ... + 2462401.

Almost surely, 2^393971440 is an apocalyptic number.

It is an amenable number.

393971440 is an abundant number, since it is smaller than the sum of its proper divisors (522012344).

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

393971440 is a wasteful number, since it uses less digits than its factorization.

393971440 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4924656 (or 4924650 counting only the distinct ones).

The product of its (nonzero) digits is 81648, while the sum is 40.

The square root of 393971440 is about 19848.7138122348. The cubic root of 393971440 is about 733.0859790190.

The spelling of 393971440 in words is "three hundred ninety-three million, nine hundred seventy-one thousand, four hundred forty".