61616221 has 4 divisors (see below), whose sum is σ = 64859200. Its totient is φ = 58373244.

The previous prime is 61616173. The next prime is 61616227. The reversal of 61616221 is 12261616.

61616221 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, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is not a de Polignac number, because 61616221 - 2²¹ = 59519069 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (61616227) 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, 1621461 + ... + 1621498.

It is an arithmetic number, because the mean of its divisors is an integer number (16214800).

Almost surely, 2^61616221 is an apocalyptic number.

It is an amenable number.

61616221 is a deficient number, since it is larger than the sum of its proper divisors (3242979).

61616221 is a wasteful number, since it uses less digits than its factorization.

61616221 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3242978.

The product of its digits is 864, while the sum is 25.

The square root of 61616221 is about 7849.6000535059. The cubic root of 61616221 is about 394.9708273066.

Adding to 61616221 its reverse (12261616), we get a palindrome (73877837).

The spelling of 61616221 in words is "sixty-one million, six hundred sixteen thousand, two hundred twenty-one".