31842721 has 2 divisors, whose sum is σ = 31842722. Its totient is φ = 31842720.

The previous prime is 31842703. The next prime is 31842739. The reversal of 31842721 is 12724813.

It is a balanced prime because it is at equal distance from previous prime (31842703) and next prime (31842739).

It can be written as a sum of positive squares in only one way, i.e., 19140625 + 12702096 = 4375^2 + 3564^2 .

It is a cyclic number.

It is not a de Polignac number, because 31842721 - 2⁷ = 31842593 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 31842721.

It is not a weakly prime, because it can be changed into another prime (31842761) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 15921360 + 15921361.

It is an arithmetic number, because the mean of its divisors is an integer number (15921361).

Almost surely, 2^31842721 is an apocalyptic number.

It is an amenable number.

31842721 is a deficient number, since it is larger than the sum of its proper divisors (1).

31842721 is an equidigital number, since it uses as much as digits as its factorization.

31842721 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 2688, while the sum is 28.

The square root of 31842721 is about 5642.9354949352. The cubic root of 31842721 is about 316.9592208056.

The spelling of 31842721 in words is "thirty-one million, eight hundred forty-two thousand, seven hundred twenty-one".