66381731 has 4 divisors (see below), whose sum is σ = 71488032. Its totient is φ = 61275432.

The previous prime is 66381713. The next prime is 66381743. The reversal of 66381731 is 13718366.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 13718366 = 2 ⋅6859183.

It is a cyclic number.

It is not a de Polignac number, because 66381731 - 2¹⁸ = 66119587 is a prime.

It is a super-2 number, since 2×66381731² = 8813068421112722, which contains 22 as substring.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 66381691 and 66381700.

It is not an unprimeable number, because it can be changed into a prime (66381701) 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, 2553131 + ... + 2553156.

It is an arithmetic number, because the mean of its divisors is an integer number (17872008).

Almost surely, 2^66381731 is an apocalyptic number.

66381731 is a deficient number, since it is larger than the sum of its proper divisors (5106301).

66381731 is a wasteful number, since it uses less digits than its factorization.

66381731 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 5106300.

The product of its digits is 18144, while the sum is 35.

The square root of 66381731 is about 8147.4984504448. The cubic root of 66381731 is about 404.9016293119.

The spelling of 66381731 in words is "sixty-six million, three hundred eighty-one thousand, seven hundred thirty-one".