64400400 has 240 divisors, whose sum is σ = 235252800. Its totient is φ = 16727040.

The previous prime is 64400389. The next prime is 64400407. The reversal of 64400400 is 400446.

It is a tau number, because it is divible by the number of its divisors (240).

It is a Harshad number since it is a multiple of its sum of digits (18).

It is not an unprimeable number, because it can be changed into a prime (64400407) by changing a digit.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 723556 + ... + 723644.

It is an arithmetic number, because the mean of its divisors is an integer number (980220).

Almost surely, 2^64400400 is an apocalyptic number.

64400400 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 64400400, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (117626400).

64400400 is an abundant number, since it is smaller than the sum of its proper divisors (170852400).

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

64400400 is a wasteful number, since it uses less digits than its factorization.

64400400 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 183 (or 166 counting only the distinct ones).

The product of its (nonzero) digits is 384, while the sum is 18.

The square root of 64400400 is about 8024.9859812962. The cubic root of 64400400 is about 400.8324331028.

Adding to 64400400 its reverse (400446), we get a palindrome (64800846).

The spelling of 64400400 in words is "sixty-four million, four hundred thousand, four hundred".