393910421 has 4 divisors (see below), whose sum is σ = 394185600. Its totient is φ = 393635244.

The previous prime is 393910381. The next prime is 393910427. The reversal of 393910421 is 124019393.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4, and also an emirpimes, since its reverse is a distinct semiprime: 124019393 = 1117 ⋅111029.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-393910421 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (393910427) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 135431 + ... + 138308.

It is an arithmetic number, because the mean of its divisors is an integer number (98546400).

Almost surely, 2^393910421 is an apocalyptic number.

It is an amenable number.

393910421 is a deficient number, since it is larger than the sum of its proper divisors (275179).

393910421 is a wasteful number, since it uses less digits than its factorization.

393910421 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 275178.

The product of its (nonzero) digits is 5832, while the sum is 32.

The square root of 393910421 is about 19847.1766505969. The cubic root of 393910421 is about 733.0481298432.

The spelling of 393910421 in words is "three hundred ninety-three million, nine hundred ten thousand, four hundred twenty-one".