31287689 has 2 divisors, whose sum is σ = 31287690. Its totient is φ = 31287688.

The previous prime is 31287677. The next prime is 31287691. The reversal of 31287689 is 98678213.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 25928464 + 5359225 = 5092^2 + 2315^2 .

It is a cyclic number.

It is not a de Polignac number, because 31287689 - 2⁴ = 31287673 is a prime.

Together with 31287691, it forms a pair of twin primes.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (31287629) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 15643844 + 15643845.

It is an arithmetic number, because the mean of its divisors is an integer number (15643845).

Almost surely, 2^31287689 is an apocalyptic number.

It is an amenable number.

31287689 is a deficient number, since it is larger than the sum of its proper divisors (1).

31287689 is an equidigital number, since it uses as much as digits as its factorization.

31287689 is an evil number, because the sum of its binary digits is even.

The product of its digits is 145152, while the sum is 44.

The square root of 31287689 is about 5593.5399346031. The cubic root of 31287689 is about 315.1068387069.

The spelling of 31287689 in words is "thirty-one million, two hundred eighty-seven thousand, six hundred eighty-nine".