65809920 has 320 divisors, whose sum is σ = 247484160. Its totient is φ = 14745600.

The previous prime is 65809867. The next prime is 65809921. The reversal of 65809920 is 2990856.

65809920 = T₂₂₉ + T₂₃₀ + ... + T₇₄₀.

It is a happy number.

It is a tau number, because it is divible by the number of its divisors (320).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (65809921) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 1605100 + ... + 1605140.

It is an arithmetic number, because the mean of its divisors is an integer number (773388).

Almost surely, 2^65809920 is an apocalyptic number.

65809920 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 65809920, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (123742080).

65809920 is an abundant number, since it is smaller than the sum of its proper divisors (181674240).

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

65809920 is a wasteful number, since it uses less digits than its factorization.

65809920 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 97 (or 81 counting only the distinct ones).

The product of its (nonzero) digits is 38880, while the sum is 39.

The square root of 65809920 is about 8112.3313541793. The cubic root of 65809920 is about 403.7356699825.

The spelling of 65809920 in words is "sixty-five million, eight hundred nine thousand, nine hundred twenty".