66215381 has 8 divisors (see below), whose sum is σ = 69465600. Its totient is φ = 63029680.

The previous prime is 66215353. The next prime is 66215389. The reversal of 66215381 is 18351266.

It is a happy number.

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 66215381 - 2¹⁴ = 66198997 is a prime.

It is a super-2 number, since 2×66215381² = 8768953361950322, which contains 22 as substring.

It is a Duffinian number.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (66215389) 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 7 ways as a sum of consecutive naturals, for example, 14021 + ... + 18138.

It is an arithmetic number, because the mean of its divisors is an integer number (8683200).

Almost surely, 2^66215381 is an apocalyptic number.

It is an amenable number.

66215381 is a deficient number, since it is larger than the sum of its proper divisors (3250219).

66215381 is a wasteful number, since it uses less digits than its factorization.

66215381 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 32259.

The product of its digits is 8640, while the sum is 32.

The square root of 66215381 is about 8137.2833918944. The cubic root of 66215381 is about 404.5631238888.

The spelling of 66215381 in words is "sixty-six million, two hundred fifteen thousand, three hundred eighty-one".