66939409 has 8 divisors (see below), whose sum is σ = 68037480. Its totient is φ = 65849856.

The previous prime is 66939403. The next prime is 66939419. The reversal of 66939409 is 90493966.

It can be written as a sum of positive squares in 4 ways, for example, as 20903184 + 46036225 = 4572^2 + 6785^2 .

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 66939409 - 2¹⁵ = 66906641 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (66939403) 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, 14787 + ... + 18775.

It is an arithmetic number, because the mean of its divisors is an integer number (8504685).

Almost surely, 2^66939409 is an apocalyptic number.

It is an amenable number.

66939409 is a deficient number, since it is larger than the sum of its proper divisors (1098071).

66939409 is a wasteful number, since it uses less digits than its factorization.

66939409 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4259.

The product of its (nonzero) digits is 314928, while the sum is 46.

The square root of 66939409 is about 8181.6507503071. The cubic root of 66939409 is about 406.0323386602.

The spelling of 66939409 in words is "sixty-six million, nine hundred thirty-nine thousand, four hundred nine".