63216561 has 4 divisors (see below), whose sum is σ = 84288752. Its totient is φ = 42144372.

The previous prime is 63216541. The next prime is 63216583. The reversal of 63216561 is 16561236.

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 not a de Polignac number, because 63216561 - 2⁶ = 63216497 is a prime.

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

It is a Duffinian number.

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (63216541) 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, 10536091 + ... + 10536096.

It is an arithmetic number, because the mean of its divisors is an integer number (21072188).

Almost surely, 2^63216561 is an apocalyptic number.

It is an amenable number.

63216561 is a deficient number, since it is larger than the sum of its proper divisors (21072191).

63216561 is a wasteful number, since it uses less digits than its factorization.

63216561 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 21072190.

The product of its digits is 6480, while the sum is 30.

The square root of 63216561 is about 7950.8842904422. The cubic root of 63216561 is about 398.3611298487.

Adding to 63216561 its reverse (16561236), we get a palindrome (79777797).

The spelling of 63216561 in words is "sixty-three million, two hundred sixteen thousand, five hundred sixty-one".