31321289 has 2 divisors, whose sum is σ = 31321290. Its totient is φ = 31321288.

The previous prime is 31321273. The next prime is 31321309. The reversal of 31321289 is 98212313.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 30525625 + 795664 = 5525^2 + 892^2 .

It is a cyclic number.

It is not a de Polignac number, because 31321289 - 2⁴ = 31321273 is a prime.

It is a Sophie Germain prime.

It is a Curzon number.

It is equal to p_1934552 and since 31321289 and 1934552 have the same sum of digits, it is a Honaker prime.

It is not a weakly prime, because it can be changed into another prime (31321219) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 15660644 + 15660645.

It is an arithmetic number, because the mean of its divisors is an integer number (15660645).

Almost surely, 2^31321289 is an apocalyptic number.

It is an amenable number.

31321289 is a deficient number, since it is larger than the sum of its proper divisors (1).

31321289 is an equidigital number, since it uses as much as digits as its factorization.

31321289 is an evil number, because the sum of its binary digits is even.

The product of its digits is 2592, while the sum is 29.

The square root of 31321289 is about 5596.5425934232. The cubic root of 31321289 is about 315.2195966036.

The spelling of 31321289 in words is "thirty-one million, three hundred twenty-one thousand, two hundred eighty-nine".