65981440 has 132 divisors (see below), whose sum is σ = 184819536. Its totient is φ = 22536192.

The previous prime is 65981429. The next prime is 65981441. The reversal of 65981440 is 4418956.

It is a happy number.

It is a self number, because there is not a number n which added to its sum of digits gives 65981440.

It is not an unprimeable number, because it can be changed into a prime (65981441) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 250749 + ... + 251011.

It is an arithmetic number, because the mean of its divisors is an integer number (1400148).

Almost surely, 2^65981440 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 65981440, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (92409768).

65981440 is an abundant number, since it is smaller than the sum of its proper divisors (118838096).

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

65981440 is a wasteful number, since it uses less digits than its factorization.

65981440 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 302 (or 277 counting only the distinct ones).

The product of its (nonzero) digits is 34560, while the sum is 37.

The square root of 65981440 is about 8122.8960352820. The cubic root of 65981440 is about 404.0861169881.

The spelling of 65981440 in words is "sixty-five million, nine hundred eighty-one thousand, four hundred forty".