394539521 has 4 divisors (see below), whose sum is σ = 401007444. Its totient is φ = 388071600.

The previous prime is 394539437. The next prime is 394539571. The reversal of 394539521 is 125935493.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 125935493 = 8237 ⋅15289.

It can be written as a sum of positive squares in 2 ways, for example, as 178596496 + 215943025 = 13364^2 + 14695^2 .

It is a cyclic number.

It is not a de Polignac number, because 394539521 - 2¹⁰ = 394538497 is a prime.

It is a super-2 number, since 2×394539521² = 311322867261818882, which contains 22 as substring.

It is a Duffinian number.

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (394539571) 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, 3233870 + ... + 3233991.

It is an arithmetic number, because the mean of its divisors is an integer number (100251861).

Almost surely, 2^394539521 is an apocalyptic number.

It is an amenable number.

394539521 is a deficient number, since it is larger than the sum of its proper divisors (6467923).

394539521 is an equidigital number, since it uses as much as digits as its factorization.

394539521 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 6467922.

The product of its digits is 145800, while the sum is 41.

The square root of 394539521 is about 19863.0189296592. The cubic root of 394539521 is about 733.4381637786.

The spelling of 394539521 in words is "three hundred ninety-four million, five hundred thirty-nine thousand, five hundred twenty-one".