65521220 has 12 divisors (see below), whose sum is σ = 137594604. Its totient is φ = 26208480.

The previous prime is 65521219. The next prime is 65521241. The reversal of 65521220 is 2212556.

It can be written as a sum of positive squares in 2 ways, for example, as 10137856 + 55383364 = 3184^2 + 7442^2 .

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 1638011 + ... + 1638050.

It is an arithmetic number, because the mean of its divisors is an integer number (11466217).

Almost surely, 2^65521220 is an apocalyptic number.

It is an amenable number.

65521220 is an abundant number, since it is smaller than the sum of its proper divisors (72073384).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

65521220 is a wasteful number, since it uses less digits than its factorization.

65521220 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3276070 (or 3276068 counting only the distinct ones).

The product of its (nonzero) digits is 1200, while the sum is 23.

The square root of 65521220 is about 8094.5178979356. The cubic root of 65521220 is about 403.1444250400.

Adding to 65521220 its reverse (2212556), we get a palindrome (67733776).

The spelling of 65521220 in words is "sixty-five million, five hundred twenty-one thousand, two hundred twenty".