31728457 has 2 divisors, whose sum is σ = 31728458. Its totient is φ = 31728456.

The previous prime is 31728451. The next prime is 31728467. The reversal of 31728457 is 75482713.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 20331081 + 11397376 = 4509^2 + 3376^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-31728457 is a prime.

It is equal to p_1958059 and since 31728457 and 1958059 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 (31728451) by changing a digit.

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

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 15864228 + 15864229.

It is an arithmetic number, because the mean of its divisors is an integer number (15864229).

Almost surely, 2^31728457 is an apocalyptic number.

It is an amenable number.

31728457 is a deficient number, since it is larger than the sum of its proper divisors (1).

31728457 is an equidigital number, since it uses as much as digits as its factorization.

31728457 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 47040, while the sum is 37.

The square root of 31728457 is about 5632.8018782840. The cubic root of 31728457 is about 316.5796423225.

The spelling of 31728457 in words is "thirty-one million, seven hundred twenty-eight thousand, four hundred fifty-seven".