31209109 has 2 divisors, whose sum is σ = 31209110. Its totient is φ = 31209108.

The previous prime is 31209067. The next prime is 31209119. The reversal of 31209109 is 90190213.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 18464209 + 12744900 = 4297^2 + 3570^2 .

It is an emirp because it is prime and its reverse (90190213) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 31209109 - 2⁷ = 31208981 is a prime.

It is equal to p_1928023 and since 31209109 and 1928023 have the same sum of digits, it is a Honaker prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (31209119) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 15604554 + 15604555.

It is an arithmetic number, because the mean of its divisors is an integer number (15604555).

Almost surely, 2^31209109 is an apocalyptic number.

It is an amenable number.

31209109 is a deficient number, since it is larger than the sum of its proper divisors (1).

31209109 is an equidigital number, since it uses as much as digits as its factorization.

31209109 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 486, while the sum is 25.

The square root of 31209109 is about 5586.5113443007. The cubic root of 31209109 is about 314.8428173557.

The spelling of 31209109 in words is "thirty-one million, two hundred nine thousand, one hundred nine".