52216721 has 4 divisors (see below), whose sum is σ = 52288692. Its totient is φ = 52144752.

The previous prime is 52216699. The next prime is 52216727. The reversal of 52216721 is 12761225.

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 28206721 + 24010000 = 5311^2 + 4900^2 .

It is a cyclic number.

It is not a de Polignac number, because 52216721 - 2²² = 48022417 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (52216727) 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, 34886 + ... + 36351.

It is an arithmetic number, because the mean of its divisors is an integer number (13072173).

Almost surely, 2^52216721 is an apocalyptic number.

It is an amenable number.

52216721 is a deficient number, since it is larger than the sum of its proper divisors (71971).

52216721 is an equidigital number, since it uses as much as digits as its factorization.

52216721 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 71970.

The product of its digits is 1680, while the sum is 26.

The square root of 52216721 is about 7226.1138241796. The cubic root of 52216721 is about 373.7689313051.

Adding to 52216721 its reverse (12761225), we get a palindrome (64977946).

The spelling of 52216721 in words is "fifty-two million, two hundred sixteen thousand, seven hundred twenty-one".