65640220 has 48 divisors (see below), whose sum is σ = 143065440. Its totient is φ = 25277184.

The previous prime is 65640187. The next prime is 65640233. The reversal of 65640220 is 2204656.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 78766 + ... + 79594.

It is an arithmetic number, because the mean of its divisors is an integer number (2980530).

Almost surely, 2^65640220 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 65640220, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (71532720).

65640220 is an abundant number, since it is smaller than the sum of its proper divisors (77425220).

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

65640220 is a wasteful number, since it uses less digits than its factorization.

65640220 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 982 (or 980 counting only the distinct ones).

The product of its (nonzero) digits is 2880, while the sum is 25.

The square root of 65640220 is about 8101.8652173435. The cubic root of 65640220 is about 403.3883418056.

Adding to 65640220 its reverse (2204656), we get a palindrome (67844876).

The spelling of 65640220 in words is "sixty-five million, six hundred forty thousand, two hundred twenty".