64244640 has 48 divisors (see below), whose sum is σ = 202372128. Its totient is φ = 17131776.

The previous prime is 64244633. The next prime is 64244671. The reversal of 64244640 is 4644246.

It is a tau number, because it is divible by the number of its divisors (48).

It is a Harshad number since it is a multiple of its sum of digits (30).

It is a junction number, because it is equal to n+sod(n) for n = 64244598 and 64244607.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 66442 + ... + 67401.

It is an arithmetic number, because the mean of its divisors is an integer number (4216086).

Almost surely, 2^64244640 is an apocalyptic number.

64244640 is a gapful number since it is divisible by the number (60) formed by its first and last digit.

It is an amenable number.

64244640 is an abundant number, since it is smaller than the sum of its proper divisors (138127488).

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

64244640 is a wasteful number, since it uses less digits than its factorization.

64244640 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 133861 (or 133853 counting only the distinct ones).

The product of its (nonzero) digits is 18432, while the sum is 30.

The square root of 64244640 is about 8015.2754163535. The cubic root of 64244640 is about 400.5090186420.

Adding to 64244640 its reverse (4644246), we get a palindrome (68888886).

The spelling of 64244640 in words is "sixty-four million, two hundred forty-four thousand, six hundred forty".