63995521 has 4 divisors (see below), whose sum is σ = 64138500. Its totient is φ = 63852544.

The previous prime is 63995507. The next prime is 63995537. The reversal of 63995521 is 12559936.

It is a happy number.

63995521 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

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 54760000 + 9235521 = 7400^2 + 3039^2 .

It is a cyclic number.

It is not a de Polignac number, because 63995521 - 2¹⁵ = 63962753 is a prime.

It is a super-2 number, since 2×63995521² = 8190853416122882, which contains 22 as substring.

It is a Smith number, since the sum of its digits (40) coincides with the sum of the digits of its prime factors. Since it is squarefree, it is also a hoax number.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (63995621) 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 3 ways as a sum of consecutive naturals, for example, 70816 + ... + 71713.

It is an arithmetic number, because the mean of its divisors is an integer number (16034625).

Almost surely, 2^63995521 is an apocalyptic number.

It is an amenable number.

63995521 is a deficient number, since it is larger than the sum of its proper divisors (142979).

63995521 is a wasteful number, since it uses less digits than its factorization.

63995521 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 142978.

The product of its digits is 72900, while the sum is 40.

The square root of 63995521 is about 7999.7200576020. The cubic root of 63995521 is about 399.9906685323.

It can be divided in two parts, 63995 and 521, that added together give a square (64516 = 254²).

The spelling of 63995521 in words is "sixty-three million, nine hundred ninety-five thousand, five hundred twenty-one".