31216643 has 4 divisors (see below), whose sum is σ = 31332960. Its totient is φ = 31100328.

The previous prime is 31216631. The next prime is 31216649. The reversal of 31216643 is 34661213.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 34661213 = 5171 ⋅6703.

It is a cyclic number.

It is not a de Polignac number, because 31216643 - 2⁶ = 31216579 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (31216649) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 57755 + ... + 58292.

It is an arithmetic number, because the mean of its divisors is an integer number (7833240).

Almost surely, 2^31216643 is an apocalyptic number.

31216643 is a deficient number, since it is larger than the sum of its proper divisors (116317).

31216643 is a wasteful number, since it uses less digits than its factorization.

31216643 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 116316.

The product of its digits is 2592, while the sum is 26.

The square root of 31216643 is about 5587.1856063675. The cubic root of 31216643 is about 314.8681500765.

Adding to 31216643 its reverse (34661213), we get a palindrome (65877856).

The spelling of 31216643 in words is "thirty-one million, two hundred sixteen thousand, six hundred forty-three".