66216431 has 4 divisors (see below), whose sum is σ = 67756392. Its totient is φ = 64676472.

The previous prime is 66216427. The next prime is 66216433. The reversal of 66216431 is 13461266.

It is a happy number.

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

It is not a de Polignac number, because 66216431 - 2² = 66216427 is a prime.

It is a super-2 number, since 2×66216431² = 8769231468755522, 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 = 66216394 and 66216403.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (66216433) 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, 769916 + ... + 770001.

It is an arithmetic number, because the mean of its divisors is an integer number (16939098).

Almost surely, 2^66216431 is an apocalyptic number.

66216431 is a deficient number, since it is larger than the sum of its proper divisors (1539961).

66216431 is a wasteful number, since it uses less digits than its factorization.

66216431 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1539960.

The product of its digits is 5184, while the sum is 29.

The square root of 66216431 is about 8137.3479094850. The cubic root of 66216431 is about 404.5652623096.

Adding to 66216431 its reverse (13461266), we get a palindrome (79677697).

The spelling of 66216431 in words is "sixty-six million, two hundred sixteen thousand, four hundred thirty-one".