66921941 has 4 divisors (see below), whose sum is σ = 68019084. Its totient is φ = 65824800.

The previous prime is 66921931. The next prime is 66921961. The reversal of 66921941 is 14912966.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 14912966 = 2 ⋅7456483.

It can be written as a sum of positive squares in 2 ways, for example, as 11195716 + 55726225 = 3346^2 + 7465^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-66921941 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is a junction number, because it is equal to n+sod(n) for n = 66921895 and 66921904.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (66921931) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 548480 + ... + 548601.

It is an arithmetic number, because the mean of its divisors is an integer number (17004771).

Almost surely, 2^66921941 is an apocalyptic number.

66921941 is a gapful number since it is divisible by the number (61) formed by its first and last digit.

It is an amenable number.

66921941 is a deficient number, since it is larger than the sum of its proper divisors (1097143).

66921941 is a wasteful number, since it uses less digits than its factorization.

66921941 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1097142.

The product of its digits is 23328, while the sum is 38.

The square root of 66921941 is about 8180.5831699213. The cubic root of 66921941 is about 405.9970172154.

The spelling of 66921941 in words is "sixty-six million, nine hundred twenty-one thousand, nine hundred forty-one".