31491697 has 2 divisors, whose sum is σ = 31491698. Its totient is φ = 31491696.

The previous prime is 31491679. The next prime is 31491727. The reversal of 31491697 is 79619413.

Together with previous prime (31491679) it forms an Ormiston pair, because they use the same digits, order apart.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 28772496 + 2719201 = 5364^2 + 1649^2 .

It is a cyclic number.

It is not a de Polignac number, because 31491697 - 2²³ = 23103089 is a prime.

It is not a weakly prime, because it can be changed into another prime (31491637) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is an upside-down number.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 15745848 + 15745849.

It is an arithmetic number, because the mean of its divisors is an integer number (15745849).

Almost surely, 2^31491697 is an apocalyptic number.

It is an amenable number.

31491697 is a deficient number, since it is larger than the sum of its proper divisors (1).

31491697 is an equidigital number, since it uses as much as digits as its factorization.

31491697 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 40824, while the sum is 40.

The square root of 31491697 is about 5611.7463413807. The cubic root of 31491697 is about 315.7902289080.

The spelling of 31491697 in words is "thirty-one million, four hundred ninety-one thousand, six hundred ninety-seven".