641520 has 140 divisors (see below), whose sum is σ = 2439576. Its totient is φ = 155520.

The previous prime is 641519. The next prime is 641521. The reversal of 641520 is 25146.

It is a happy number.

641520 is a `hidden beast` number, since 641 + 5 + 20 = 666.

641520 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is an interprime number because it is at equal distance from previous prime (641519) and next prime (641521).

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

It is a zygodrome in base 9.

It is a junction number, because it is equal to n+sod(n) for n = 641493 and 641502.

It is a congruent number.

It is an inconsummate number, since it does not exist a number n which divided by its sum of digits gives 641520.

It is not an unprimeable number, because it can be changed into a prime (641521) by changing a digit.

It is a polite number, since it can be written in 27 ways as a sum of consecutive naturals, for example, 58315 + ... + 58325.

2⁶⁴¹⁵²⁰ is an apocalyptic number.

641520 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 641520, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1219788).

641520 is an abundant number, since it is smaller than the sum of its proper divisors (1798056).

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

641520 is a wasteful number, since it uses less digits than its factorization.

641520 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 42 (or 21 counting only the distinct ones).

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

The square root of 641520 is about 800.9494366063. The cubic root of 641520 is about 86.2455574271.

Adding to 641520 its reverse (25146), we get a palindrome (666666).

The spelling of 641520 in words is "six hundred forty-one thousand, five hundred twenty".