66801780 has 48 divisors (see below), whose sum is σ = 207829440. Its totient is φ = 17813664.

The previous prime is 66801769. The next prime is 66801793. The reversal of 66801780 is 8710866.

66801780 is digitally balanced in base 9, because in such base it contains all the possibile digits an equal number of times.

It is a super-2 number, since 2×66801780² = 8924955622336800, which contains 22 as substring.

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

66801780 is strictly pandigital in base 9.

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, 61314 + ... + 62393.

It is an arithmetic number, because the mean of its divisors is an integer number (4329780).

Almost surely, 2^66801780 is an apocalyptic number.

66801780 is a gapful number since it is divisible by the number (60) formed by its first and last digit.

It is an amenable number.

66801780 is an abundant number, since it is smaller than the sum of its proper divisors (141027660).

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

66801780 is a wasteful number, since it uses less digits than its factorization.

66801780 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 123725 (or 123717 counting only the distinct ones).

The product of its (nonzero) digits is 16128, while the sum is 36.

The square root of 66801780 is about 8173.2355894101. The cubic root of 66801780 is about 405.7538770510.

The spelling of 66801780 in words is "sixty-six million, eight hundred one thousand, seven hundred eighty".