66100820 has 24 divisors (see below), whose sum is σ = 141089928. Its totient is φ = 26006400.

The previous prime is 66100807. The next prime is 66100823. The reversal of 66100820 is 2800166.

It can be written as a sum of positive squares in 4 ways, for example, as 7333264 + 58767556 = 2708^2 + 7666^2 .

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (66100823) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 25871 + ... + 28310.

It is an arithmetic number, because the mean of its divisors is an integer number (5878747).

Almost surely, 2^66100820 is an apocalyptic number.

It is an amenable number.

66100820 is an abundant number, since it is smaller than the sum of its proper divisors (74989108).

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

66100820 is a wasteful number, since it uses less digits than its factorization.

66100820 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 54251 (or 54249 counting only the distinct ones).

The product of its (nonzero) digits is 576, while the sum is 23.

The square root of 66100820 is about 8130.2410788365. The cubic root of 66100820 is about 404.3296740474.

Adding to 66100820 its reverse (2800166), we get a palindrome (68900986).

The spelling of 66100820 in words is "sixty-six million, one hundred thousand, eight hundred twenty".