31388138 has 4 divisors (see below), whose sum is σ = 47082210. Its totient is φ = 15694068.

The previous prime is 31388113. The next prime is 31388141. The reversal of 31388138 is 83188313.

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

It can be written as a sum of positive squares in only one way, i.e., 18550249 + 12837889 = 4307^2 + 3583^2 .

It is a junction number, because it is equal to n+sod(n) for n = 31388098 and 31388107.

It is an unprimeable number.

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 as a sum of consecutive naturals, namely, 7847033 + ... + 7847036.

Almost surely, 2^31388138 is an apocalyptic number.

31388138 is a deficient number, since it is larger than the sum of its proper divisors (15694072).

31388138 is a wasteful number, since it uses less digits than its factorization.

31388138 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 15694071.

The product of its digits is 13824, while the sum is 35.

The square root of 31388138 is about 5602.5117581313. The cubic root of 31388138 is about 315.4436948856.

The spelling of 31388138 in words is "thirty-one million, three hundred eighty-eight thousand, one hundred thirty-eight".