65781820 has 48 divisors (see below), whose sum is σ = 150151680. Its totient is φ = 24062976.

The previous prime is 65781797. The next prime is 65781847. The reversal of 65781820 is 2818756.

It is a self number, because there is not a number n which added to its sum of digits gives 65781820.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 28261 + ... + 30499.

It is an arithmetic number, because the mean of its divisors is an integer number (3128160).

Almost surely, 2^65781820 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 65781820, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (75075840).

65781820 is an abundant number, since it is smaller than the sum of its proper divisors (84369860).

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

65781820 is a wasteful number, since it uses less digits than its factorization.

65781820 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2374 (or 2372 counting only the distinct ones).

The product of its (nonzero) digits is 26880, while the sum is 37.

The square root of 65781820 is about 8110.5992380341. The cubic root of 65781820 is about 403.6781984674.

The spelling of 65781820 in words is "sixty-five million, seven hundred eighty-one thousand, eight hundred twenty".