31388436 has 18 divisors (see below), whose sum is σ = 79343082. Its totient is φ = 10462800.

The previous prime is 31388429. The next prime is 31388449. The reversal of 31388436 is 63488313.

It is a happy number.

It can be written as a sum of positive squares in only one way, i.e., 27562500 + 3825936 = 5250^2 + 1956^2 .

It is a tau number, because it is divible by the number of its divisors (18).

It is a Smith number, since the sum of its digits (36) coincides with the sum of the digits of its prime factors.

It is a Harshad number since it is a multiple of its sum of digits (36), and also a Moran number because the ratio is a prime number: 871901 = 31388436 / (3 + 1 + 3 + 8 + 8 + 4 + 3 + 6).

It is a self number, because there is not a number n which added to its sum of digits gives 31388436.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 435915 + ... + 435986.

It is an arithmetic number, because the mean of its divisors is an integer number (4407949).

Almost surely, 2^31388436 is an apocalyptic number.

31388436 is a gapful number since it is divisible by the number (36) formed by its first and last digit.

It is an amenable number.

31388436 is an abundant number, since it is smaller than the sum of its proper divisors (47954646).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

31388436 is a wasteful number, since it uses less digits than its factorization.

31388436 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 871911 (or 871906 counting only the distinct ones).

The product of its digits is 41472, while the sum is 36.

The square root of 31388436 is about 5602.5383532824. The cubic root of 31388436 is about 315.4446931600. Note that the first 3 decimals are identical.

The spelling of 31388436 in words is "thirty-one million, three hundred eighty-eight thousand, four hundred thirty-six".