31691497 has 2 divisors, whose sum is σ = 31691498. Its totient is φ = 31691496.

The previous prime is 31691479. The next prime is 31691501. The reversal of 31691497 is 79419613.

Together with previous prime (31691479) it forms an Ormiston pair, because they use the same digits, order apart.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 31573161 + 118336 = 5619^2 + 344^2 .

It is a cyclic number.

It is not a de Polignac number, because 31691497 - 2⁷ = 31691369 is a prime.

It is not a weakly prime, because it can be changed into another prime (31691197) by changing a digit.

It is an upside-down number.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 15845748 + 15845749.

It is an arithmetic number, because the mean of its divisors is an integer number (15845749).

Almost surely, 2^31691497 is an apocalyptic number.

It is an amenable number.

31691497 is a deficient number, since it is larger than the sum of its proper divisors (1).

31691497 is an equidigital number, since it uses as much as digits as its factorization.

31691497 is an evil number, because the sum of its binary digits is even.

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

The square root of 31691497 is about 5629.5201394080. The cubic root of 31691497 is about 316.4566682798.

The spelling of 31691497 in words is "thirty-one million, six hundred ninety-one thousand, four hundred ninety-seven".