65521440 has 192 divisors, whose sum is σ = 237686400. Its totient is φ = 16837632.

The previous prime is 65521429. The next prime is 65521513. The reversal of 65521440 is 4412556.

65521440 is a `hidden beast` number, since 655 + 2 + 1 + 4 + 4 + 0 = 666.

It is a Harshad number since it is a multiple of its sum of digits (27).

It is an unprimeable number.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 125019 + ... + 125541.

It is an arithmetic number, because the mean of its divisors is an integer number (1237950).

Almost surely, 2^65521440 is an apocalyptic number.

65521440 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 65521440, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (118843200).

65521440 is an abundant number, since it is smaller than the sum of its proper divisors (172164960).

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

65521440 is a wasteful number, since it uses less digits than its factorization.

65521440 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 576 (or 562 counting only the distinct ones).

The product of its (nonzero) digits is 4800, while the sum is 27.

The square root of 65521440 is about 8094.5314873685. The cubic root of 65521440 is about 403.1448762509.

Adding to 65521440 its reverse (4412556), we get a palindrome (69933996).

The spelling of 65521440 in words is "sixty-five million, five hundred twenty-one thousand, four hundred forty".