66781625 has 8 divisors (see below), whose sum is σ = 83343624. Its totient is φ = 53425200.

The previous prime is 66781601. The next prime is 66781679. The reversal of 66781625 is 52618766.

It can be written as a sum of positive squares in 4 ways, for example, as 16384 + 66765241 = 128^2 + 8171^2 .

It is not a de Polignac number, because 66781625 - 2⁸ = 66781369 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 267002 + ... + 267251.

It is an arithmetic number, because the mean of its divisors is an integer number (10417953).

Almost surely, 2^66781625 is an apocalyptic number.

It is an amenable number.

66781625 is a deficient number, since it is larger than the sum of its proper divisors (16561999).

66781625 is an equidigital number, since it uses as much as digits as its factorization.

66781625 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 534268 (or 534258 counting only the distinct ones).

The product of its digits is 120960, while the sum is 41.

The square root of 66781625 is about 8172.0025085654. The cubic root of 66781625 is about 405.7130658031.

Subtracting from 66781625 its sum of digits (41), we obtain a square (66781584 = 8172²).

The spelling of 66781625 in words is "sixty-six million, seven hundred eighty-one thousand, six hundred twenty-five".