31213705 has 8 divisors (see below), whose sum is σ = 37969992. Its totient is φ = 24628608.

The previous prime is 31213703. The next prime is 31213709. The reversal of 31213705 is 50731213.

It can be written as a sum of positive squares in 4 ways, for example, as 8202496 + 23011209 = 2864^2 + 4797^2 .

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 31213705 - 2¹ = 31213703 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (31213703) 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 7 ways as a sum of consecutive naturals, for example, 42394 + ... + 43123.

It is an arithmetic number, because the mean of its divisors is an integer number (4746249).

Almost surely, 2^31213705 is an apocalyptic number.

It is an amenable number.

31213705 is a deficient number, since it is larger than the sum of its proper divisors (6756287).

31213705 is an equidigital number, since it uses as much as digits as its factorization.

31213705 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 85595.

The product of its (nonzero) digits is 630, while the sum is 22.

The square root of 31213705 is about 5586.9226771095. The cubic root of 31213705 is about 314.8582716745.

Adding to 31213705 its reverse (50731213), we get a palindrome (81944918).

The spelling of 31213705 in words is "thirty-one million, two hundred thirteen thousand, seven hundred five".