64643220 has 36 divisors (see below), whose sum is σ = 196084980. Its totient is φ = 17238144.

The previous prime is 64643219. The next prime is 64643221. The reversal of 64643220 is 2234646.

It is an interprime number because it is at equal distance from previous prime (64643219) and next prime (64643221).

It can be written as a sum of positive squares in 2 ways, for example, as 13749264 + 50893956 = 3708^2 + 7134^2 .

It is a tau number, because it is divible by the number of its divisors (36).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (64643221) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 179385 + ... + 179744.

It is an arithmetic number, because the mean of its divisors is an integer number (5446805).

Almost surely, 2^64643220 is an apocalyptic number.

64643220 is a gapful number since it is divisible by the number (60) formed by its first and last digit.

It is an amenable number.

64643220 is an abundant number, since it is smaller than the sum of its proper divisors (131441760).

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

64643220 is a wasteful number, since it uses less digits than its factorization.

64643220 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 359144 (or 359139 counting only the distinct ones).

The product of its (nonzero) digits is 6912, while the sum is 27.

The square root of 64643220 is about 8040.1007456375. The cubic root of 64643220 is about 401.3355772867.

Adding to 64643220 its reverse (2234646), we get a palindrome (66877866).

The spelling of 64643220 in words is "sixty-four million, six hundred forty-three thousand, two hundred twenty".