393924689021 has 2 divisors, whose sum is σ = 393924689022. Its totient is φ = 393924689020.

The previous prime is 393924688999. The next prime is 393924689069. The reversal of 393924689021 is 120986429393.

It is a happy number.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 223054065796 + 170870623225 = 472286^2 + 413365^2 .

It is a cyclic number.

It is not a de Polignac number, because 393924689021 - 2¹⁴ = 393924672637 is a prime.

It is a super-3 number, since 3×393924689021³ (a number of 36 digits) contains 333 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (393924689071) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 196962344510 + 196962344511.

It is an arithmetic number, because the mean of its divisors is an integer number (196962344511).

Almost surely, 2^393924689021 is an apocalyptic number.

It is an amenable number.

393924689021 is a deficient number, since it is larger than the sum of its proper divisors (1).

393924689021 is an equidigital number, since it uses as much as digits as its factorization.

393924689021 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 5038848, while the sum is 56.

The spelling of 393924689021 in words is "three hundred ninety-three billion, nine hundred twenty-four million, six hundred eighty-nine thousand, twenty-one".