66365820 has 72 divisors (see below), whose sum is σ = 201985056. Its totient is φ = 17638272.

The previous prime is 66365809. The next prime is 66365821. The reversal of 66365820 is 2856366.

It is a Smith number, since the sum of its digits (36) coincides with the sum of the digits of its prime factors.

It is a Harshad number since it is a multiple of its sum of digits (36).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (66365821) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 90174 + ... + 90906.

It is an arithmetic number, because the mean of its divisors is an integer number (2805348).

Almost surely, 2^66365820 is an apocalyptic number.

66365820 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 66365820, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (100992528).

66365820 is an abundant number, since it is smaller than the sum of its proper divisors (135619236).

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

66365820 is a wasteful number, since it uses less digits than its factorization.

66365820 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1251 (or 1246 counting only the distinct ones).

The product of its (nonzero) digits is 51840, while the sum is 36.

The square root of 66365820 is about 8146.5219572527. The cubic root of 66365820 is about 404.8692765118.

The spelling of 66365820 in words is "sixty-six million, three hundred sixty-five thousand, eight hundred twenty".