63613681 has 4 divisors (see below), whose sum is σ = 63891700. Its totient is φ = 63335664.

The previous prime is 63613661. The next prime is 63613721. The reversal of 63613681 is 18631636.

It is a happy number.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 54523456 + 9090225 = 7384^2 + 3015^2 .

It is a cyclic number.

It is not a de Polignac number, because 63613681 - 2⁹ = 63613169 is a prime.

It is a super-2 number, since 2×63613681² = 8093400820739522, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (63613661) 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, 138666 + ... + 139123.

It is an arithmetic number, because the mean of its divisors is an integer number (15972925).

Almost surely, 2^63613681 is an apocalyptic number.

It is an amenable number.

63613681 is a deficient number, since it is larger than the sum of its proper divisors (278019).

63613681 is a wasteful number, since it uses less digits than its factorization.

63613681 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 278018.

The product of its digits is 15552, while the sum is 34.

The square root of 63613681 is about 7975.8185159894. The cubic root of 63613681 is about 399.1935439142.

The spelling of 63613681 in words is "sixty-three million, six hundred thirteen thousand, six hundred eighty-one".