64640040 has 128 divisors (see below), whose sum is σ = 202037760. Its totient is φ = 16533504.

The previous prime is 64640021. The next prime is 64640041. The reversal of 64640040 is 4004646.

It is a Harshad number since it is a multiple of its sum of digits (24).

It is not an unprimeable number, because it can be changed into a prime (64640041) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 411642 + ... + 411798.

It is an arithmetic number, because the mean of its divisors is an integer number (1578420).

Almost surely, 2^64640040 is an apocalyptic number.

64640040 is a gapful number since it is divisible by the number (60) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 64640040, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (101018880).

64640040 is an abundant number, since it is smaller than the sum of its proper divisors (137397720).

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

64640040 is a wasteful number, since it uses less digits than its factorization.

64640040 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 291 (or 287 counting only the distinct ones).

The product of its (nonzero) digits is 2304, while the sum is 24.

The square root of 64640040 is about 8039.9029844893. The cubic root of 64640040 is about 401.3289961992.

Adding to 64640040 its reverse (4004646), we get a palindrome (68644686).

The spelling of 64640040 in words is "sixty-four million, six hundred forty thousand, forty".