64406640 has 80 divisors (see below), whose sum is σ = 205085088. Its totient is φ = 16708608.

The previous prime is 64406633. The next prime is 64406669. The reversal of 64406640 is 4660446.

64406640 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a tau number, because it is divible by the number of its divisors (80).

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 = 64406598 and 64406607.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 5254 + ... + 12506.

Almost surely, 2^64406640 is an apocalyptic number.

64406640 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 64406640, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (102542544).

64406640 is an abundant number, since it is smaller than the sum of its proper divisors (140678448).

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

64406640 is a wasteful number, since it uses less digits than its factorization.

64406640 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 7306 (or 7300 counting only the distinct ones).

The product of its (nonzero) digits is 13824, while the sum is 30.

The square root of 64406640 is about 8025.3747576048. The cubic root of 64406640 is about 400.8453787449.

The spelling of 64406640 in words is "sixty-four million, four hundred six thousand, six hundred forty".