393493998681 has 63 divisors (see below), whose sum is σ = 686499765381. Its totient is φ = 224785966104.

The previous prime is 393493998679. The next prime is 393493998697. The reversal of 393493998681 is 186899394393.

The square root of 393493998681 is 627291.

It is a perfect power (a square), and thus also a powerful number.

393493998681 is a `hidden beast` number, since 393 + 4 + 93 + 9 + 98 + 68 + 1 = 666.

It is a tau number, because it is divible by the number of its divisors (63).

It is not a de Polignac number, because 393493998681 - 2¹ = 393493998679 is a prime.

It is a super-2 number, since 2×393493998681² (a number of 24 digits) contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (393493998881) by changing a digit.

It is a polite number, since it can be written in 62 ways as a sum of consecutive naturals, for example, 118556340 + ... + 118559658.

Almost surely, 2^393493998681 is an apocalyptic number.

393493998681 is the 627291-st square number.

393493998681 is the 313646-th centered octagonal number.

It is an amenable number.

393493998681 is a deficient number, since it is larger than the sum of its proper divisors (293005766700).

393493998681 is an frugal number, since it uses more digits than its factorization.

393493998681 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 6670 (or 3329 counting only the distinct ones).

The product of its digits is 272097792, while the sum is 72.

The spelling of 393493998681 in words is "three hundred ninety-three billion, four hundred ninety-three million, nine hundred ninety-eight thousand, six hundred eighty-one".