64381440 has 160 divisors (see below), whose sum is σ = 210361536. Its totient is φ = 16793600.

The previous prime is 64381409. The next prime is 64381441. The reversal of 64381440 is 4418346.

It is a tau number, because it is divible by the number of its divisors (160).

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 = 64381398 and 64381407.

It is not an unprimeable number, because it can be changed into a prime (64381441) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 637390 + ... + 637490.

Almost surely, 2^64381440 is an apocalyptic number.

64381440 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 64381440, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (105180768).

64381440 is an abundant number, since it is smaller than the sum of its proper divisors (145980096).

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

64381440 is a wasteful number, since it uses less digits than its factorization.

64381440 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 210 (or 194 counting only the distinct ones).

The product of its (nonzero) digits is 9216, while the sum is 30.

The square root of 64381440 is about 8023.8045838617. The cubic root of 64381440 is about 400.7930931356.

Adding to 64381440 its reverse (4418346), we get a palindrome (68799786).

The spelling of 64381440 in words is "sixty-four million, three hundred eighty-one thousand, four hundred forty".