31438991 has 4 divisors (see below), whose sum is σ = 32453184. Its totient is φ = 30424800.

The previous prime is 31438963. The next prime is 31438993. The reversal of 31438991 is 19983413.

It is a happy number.

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

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-31438991 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (31438993) by changing a digit.

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 in 3 ways as a sum of consecutive naturals, for example, 507050 + ... + 507111.

It is an arithmetic number, because the mean of its divisors is an integer number (8113296).

Almost surely, 2^31438991 is an apocalyptic number.

31438991 is a gapful number since it is divisible by the number (31) formed by its first and last digit.

31438991 is a deficient number, since it is larger than the sum of its proper divisors (1014193).

31438991 is a wasteful number, since it uses less digits than its factorization.

31438991 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1014192.

The product of its digits is 23328, while the sum is 38.

The square root of 31438991 is about 5607.0483322333. The cubic root of 31438991 is about 315.6139566897.

It can be divided in two parts, 31 and 438991, that multiplied together give a square (13608721 = 3689²).

The spelling of 31438991 in words is "thirty-one million, four hundred thirty-eight thousand, nine hundred ninety-one".