65661220 has 24 divisors (see below), whose sum is σ = 142644600. Its totient is φ = 25358592.

The previous prime is 65661181. The next prime is 65661221. The reversal of 65661220 is 2216656.

It can be written as a sum of positive squares in 4 ways, for example, as 15194404 + 50466816 = 3898^2 + 7104^2 .

It is a super-2 number, since 2×65661220² = 8622791623776800, which contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (65661221) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 56025 + ... + 57184.

It is an arithmetic number, because the mean of its divisors is an integer number (5943525).

Almost surely, 2^65661220 is an apocalyptic number.

It is an amenable number.

65661220 is an abundant number, since it is smaller than the sum of its proper divisors (76983380).

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

65661220 is a wasteful number, since it uses less digits than its factorization.

65661220 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 113247 (or 113245 counting only the distinct ones).

The product of its (nonzero) digits is 4320, while the sum is 28.

The square root of 65661220 is about 8103.1611115663. The cubic root of 65661220 is about 403.4313553318.

Adding to 65661220 its reverse (2216656), we get a palindrome (67877876).

The spelling of 65661220 in words is "sixty-five million, six hundred sixty-one thousand, two hundred twenty".