33129721 has 2 divisors, whose sum is σ = 33129722. Its totient is φ = 33129720.

The previous prime is 33129713. The next prime is 33129757. The reversal of 33129721 is 12792133.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 32936121 + 193600 = 5739^2 + 440^2 .

It is a cyclic number.

It is not a de Polignac number, because 33129721 - 2³ = 33129713 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 33129721.

It is not a weakly prime, because it can be changed into another prime (33129781) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 16564860 + 16564861.

It is an arithmetic number, because the mean of its divisors is an integer number (16564861).

Almost surely, 2^33129721 is an apocalyptic number.

It is an amenable number.

33129721 is a deficient number, since it is larger than the sum of its proper divisors (1).

33129721 is an equidigital number, since it uses as much as digits as its factorization.

33129721 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 2268, while the sum is 28.

The square root of 33129721 is about 5755.8423362702. The cubic root of 33129721 is about 321.1731709261.

The spelling of 33129721 in words is "thirty-three million, one hundred twenty-nine thousand, seven hundred twenty-one".