6401520 has 120 divisors (see below), whose sum is σ = 22806576. Its totient is φ = 1603584.

The previous prime is 6401509. The next prime is 6401533. The reversal of 6401520 is 251046.

It is a happy number.

6401520 is a `hidden beast` number, since 640 + 1 + 5 + 20 = 666.

6401520 is digitally balanced in base 4 and base 5, because in such bases 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 (120).

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

It is a junction number, because it is equal to n+sod(n) for n = 6401493 and 6401502.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 11979 + ... + 12501.

Almost surely, 2^6401520 is an apocalyptic number.

6401520 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 6401520, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (11403288).

6401520 is an abundant number, since it is smaller than the sum of its proper divisors (16405056).

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

6401520 is a wasteful number, since it uses less digits than its factorization.

6401520 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 559 (or 550 counting only the distinct ones).

The product of its (nonzero) digits is 240, while the sum is 18.

The square root of 6401520 is about 2530.1225266773. The cubic root of 6401520 is about 185.6782505457.

Adding to 6401520 its reverse (251046), we get a palindrome (6652566).

The spelling of 6401520 in words is "six million, four hundred one thousand, five hundred twenty".