64511221 has 4 divisors (see below), whose sum is σ = 65568844. Its totient is φ = 63453600.

The previous prime is 64511207. The next prime is 64511231. The reversal of 64511221 is 12211546.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 12211546 = 2 ⋅6105773.

It can be written as a sum of positive squares in 2 ways, for example, as 29866225 + 34644996 = 5465^2 + 5886^2 .

It is a cyclic number.

It is not a de Polignac number, because 64511221 - 2⁹ = 64510709 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 64511192 and 64511201.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (64511231) 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, 528720 + ... + 528841.

It is an arithmetic number, because the mean of its divisors is an integer number (16392211).

Almost surely, 2^64511221 is an apocalyptic number.

64511221 is a gapful number since it is divisible by the number (61) formed by its first and last digit.

It is an amenable number.

64511221 is a deficient number, since it is larger than the sum of its proper divisors (1057623).

64511221 is a wasteful number, since it uses less digits than its factorization.

64511221 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1057622.

The product of its digits is 480, while the sum is 22.

The square root of 64511221 is about 8031.8877606700. The cubic root of 64511221 is about 401.0622204723.

Adding to 64511221 its reverse (12211546), we get a palindrome (76722767).

The spelling of 64511221 in words is "sixty-four million, five hundred eleven thousand, two hundred twenty-one".