63915989781 has 36 divisors (see below), whose sum is σ = 99791266848. Its totient is φ = 35646235632.

The previous prime is 63915989747. The next prime is 63915989801. The reversal of 63915989781 is 18798951936.

63915989781 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is not a de Polignac number, because 63915989781 - 2¹⁰ = 63915988757 is a prime.

It is a super-3 number, since 3×63915989781³ (a number of 33 digits) contains 333 as substring. Note that it is a super-d number also for d = 2.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (63915989881) by changing a digit.

It is a polite number, since it can be written in 35 ways as a sum of consecutive naturals, for example, 49816966 + ... + 49818248.

Almost surely, 2^63915989781 is an apocalyptic number.

It is an amenable number.

63915989781 is a deficient number, since it is larger than the sum of its proper divisors (35875277067).

63915989781 is an frugal number, since it uses more digits than its factorization.

63915989781 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2662 (or 1336 counting only the distinct ones).

The product of its digits is 29393280, while the sum is 66.

The spelling of 63915989781 in words is "sixty-three billion, nine hundred fifteen million, nine hundred eighty-nine thousand, seven hundred eighty-one".