65978640 has 480 divisors, whose sum is σ = 292481280. Its totient is φ = 12939264.

The previous prime is 65978639. The next prime is 65978657. The reversal of 65978640 is 4687956.

It is a Harshad number since it is a multiple of its sum of digits (45).

It is an unprimeable number.

It is a polite number, since it can be written in 95 ways as a sum of consecutive naturals, for example, 1244854 + ... + 1244906.

It is an arithmetic number, because the mean of its divisors is an integer number (609336).

Almost surely, 2^65978640 is an apocalyptic number.

65978640 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 65978640, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (146240640).

65978640 is an abundant number, since it is smaller than the sum of its proper divisors (226502640).

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

65978640 is a wasteful number, since it uses less digits than its factorization.

65978640 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 111 (or 102 counting only the distinct ones).

The product of its (nonzero) digits is 362880, while the sum is 45.

The square root of 65978640 is about 8122.7236811306. The cubic root of 65978640 is about 404.0804009508.

The spelling of 65978640 in words is "sixty-five million, nine hundred seventy-eight thousand, six hundred forty".