31638361 has 4 divisors (see below), whose sum is σ = 31652532. Its totient is φ = 31624192.

The previous prime is 31638359. The next prime is 31638389. The reversal of 31638361 is 16383613.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 16383613 = 23 ⋅712331.

It can be written as a sum of positive squares in 2 ways, for example, as 13838400 + 17799961 = 3720^2 + 4219^2 .

It is a cyclic number.

It is not a de Polignac number, because 31638361 - 2¹ = 31638359 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (31638301) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 2920 + ... + 8473.

It is an arithmetic number, because the mean of its divisors is an integer number (7913133).

Almost surely, 2^31638361 is an apocalyptic number.

It is an amenable number.

31638361 is a deficient number, since it is larger than the sum of its proper divisors (14171).

31638361 is a wasteful number, since it uses less digits than its factorization.

31638361 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 14170.

The product of its digits is 7776, while the sum is 31.

The square root of 31638361 is about 5624.7987519555. The cubic root of 31638361 is about 316.2797054799.

The spelling of 31638361 in words is "thirty-one million, six hundred thirty-eight thousand, three hundred sixty-one".