31009 has 4 divisors (see below), whose sum is σ = 33840. Its totient is φ = 28180.

The previous prime is 30983. The next prime is 31013. The reversal of 31009 is 90013.

31009 = 48² + 49² + ... + 58².

It is a happy number.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 31009 - 2⁵ = 30977 is a prime.

It is a Duffinian number.

It is a nialpdrome in base 8.

It is a self number, because there is not a number n which added to its sum of digits gives 31009.

It is not an unprimeable number, because it can be changed into a prime (31019) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (7) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 1399 + ... + 1420.

It is an arithmetic number, because the mean of its divisors is an integer number (8460).

2³¹⁰⁰⁹ is an apocalyptic number.

It is an amenable number.

31009 is a deficient number, since it is larger than the sum of its proper divisors (2831).

31009 is a wasteful number, since it uses less digits than its factorization.

31009 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2830.

The product of its (nonzero) digits is 27, while the sum is 13.

The square root of 31009 is about 176.0937250444. The cubic root of 31009 is about 31.4168462756.

The spelling of 31009 in words is "thirty-one thousand, nine".