63636781 has 12 divisors (see below), whose sum is σ = 70777812. Its totient is φ = 57148416.

The previous prime is 63636761. The next prime is 63636863. The reversal of 63636781 is 18763636.

63636781 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It can be written as a sum of positive squares in 6 ways, for example, as 434281 + 63202500 = 659^2 + 7950^2 .

It is not a de Polignac number, because 63636781 - 2¹³ = 63628589 is a prime.

It is a super-2 number, since 2×63636781² = 8099279792083922, which contains 22 as substring.

It is an alternating number because its digits alternate between even and odd.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (63636761) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 1165 + ... + 11341.

It is an arithmetic number, because the mean of its divisors is an integer number (5898151).

Almost surely, 2^63636781 is an apocalyptic number.

It is an amenable number.

63636781 is a deficient number, since it is larger than the sum of its proper divisors (7141031).

63636781 is a wasteful number, since it uses less digits than its factorization.

63636781 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 10240 (or 10227 counting only the distinct ones).

The product of its digits is 108864, while the sum is 40.

The square root of 63636781 is about 7977.2665117821. The cubic root of 63636781 is about 399.2418577085.

The spelling of 63636781 in words is "sixty-three million, six hundred thirty-six thousand, seven hundred eighty-one".