66769921 has 4 divisors (see below), whose sum is σ = 66786772. Its totient is φ = 66753072.

The previous prime is 66769909. The next prime is 66769949. The reversal of 66769921 is 12996766.

66769921 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 52998400 + 13771521 = 7280^2 + 3711^2 .

It is a cyclic number.

It is not a de Polignac number, because 66769921 - 2¹³ = 66761729 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (66769981) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 1135 + ... + 11611.

It is an arithmetic number, because the mean of its divisors is an integer number (16696693).

Almost surely, 2^66769921 is an apocalyptic number.

It is an amenable number.

66769921 is a deficient number, since it is larger than the sum of its proper divisors (16851).

66769921 is a wasteful number, since it uses less digits than its factorization.

66769921 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 16850.

The product of its digits is 244944, while the sum is 46.

The square root of 66769921 is about 8171.2863736379. The cubic root of 66769921 is about 405.6893629600.

The spelling of 66769921 in words is "sixty-six million, seven hundred sixty-nine thousand, nine hundred twenty-one".