63540721 has 4 divisors (see below), whose sum is σ = 63745344. Its totient is φ = 63336100.

The previous prime is 63540709. The next prime is 63540739. The reversal of 63540721 is 12704536.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 63540721 - 2⁵ = 63540689 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 63540721.

It is not an unprimeable number, because it can be changed into a prime (63540761) 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, 101845 + ... + 102466.

It is an arithmetic number, because the mean of its divisors is an integer number (15936336).

Almost surely, 2^63540721 is an apocalyptic number.

It is an amenable number.

63540721 is a deficient number, since it is larger than the sum of its proper divisors (204623).

63540721 is a wasteful number, since it uses less digits than its factorization.

63540721 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 204622.

The product of its (nonzero) digits is 5040, while the sum is 28.

The square root of 63540721 is about 7971.2433785452. The cubic root of 63540721 is about 399.0408707660.

It can be divided in two parts, 63540 and 721, that added together give a triangular number (64261 = T₃₅₈).

The spelling of 63540721 in words is "sixty-three million, five hundred forty thousand, seven hundred twenty-one".