394456921 has 4 divisors (see below), whose sum is σ = 394635492. Its totient is φ = 394278352.

The previous prime is 394456913. The next prime is 394456943. The reversal of 394456921 is 129654493.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 129654493 = 31 ⋅4182403.

It can be written as a sum of positive squares in 2 ways, for example, as 297217600 + 97239321 = 17240^2 + 9861^2 .

It is a cyclic number.

It is not a de Polignac number, because 394456921 - 2³ = 394456913 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (394456961) 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, 85930 + ... + 90403.

It is an arithmetic number, because the mean of its divisors is an integer number (98658873).

Almost surely, 2^394456921 is an apocalyptic number.

It is an amenable number.

394456921 is a deficient number, since it is larger than the sum of its proper divisors (178571).

394456921 is a wasteful number, since it uses less digits than its factorization.

394456921 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 178570.

The product of its digits is 233280, while the sum is 43.

The square root of 394456921 is about 19860.9395799897. The cubic root of 394456921 is about 733.3869764937.

The spelling of 394456921 in words is "three hundred ninety-four million, four hundred fifty-six thousand, nine hundred twenty-one".