66770820 has 36 divisors (see below), whose sum is σ = 202538700. Its totient is φ = 17805504.

The previous prime is 66770801. The next prime is 66770827. The reversal of 66770820 is 2807766.

It can be written as a sum of positive squares in 2 ways, for example, as 48776256 + 17994564 = 6984^2 + 4242^2 .

It is a tau number, because it is divible by the number of its divisors (36).

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

It is not an unprimeable number, because it can be changed into a prime (66770827) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 185295 + ... + 185654.

It is an arithmetic number, because the mean of its divisors is an integer number (5626075).

Almost surely, 2^66770820 is an apocalyptic number.

66770820 is a gapful number since it is divisible by the number (60) formed by its first and last digit.

It is an amenable number.

66770820 is an abundant number, since it is smaller than the sum of its proper divisors (135767880).

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

66770820 is a wasteful number, since it uses less digits than its factorization.

66770820 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 370964 (or 370959 counting only the distinct ones).

The product of its (nonzero) digits is 28224, while the sum is 36.

The square root of 66770820 is about 8171.3413831512. The cubic root of 66770820 is about 405.6911837055.

The spelling of 66770820 in words is "sixty-six million, seven hundred seventy thousand, eight hundred twenty".