33981721 has 2 divisors, whose sum is σ = 33981722. Its totient is φ = 33981720.

The previous prime is 33981683. The next prime is 33981733. The reversal of 33981721 is 12718933.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 33235225 + 746496 = 5765^2 + 864^2 .

It is an emirp because it is prime and its reverse (12718933) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 33981721 - 2²¹ = 31884569 is a prime.

It is not a weakly prime, because it can be changed into another prime (33981421) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 16990860 + 16990861.

It is an arithmetic number, because the mean of its divisors is an integer number (16990861).

Almost surely, 2^33981721 is an apocalyptic number.

It is an amenable number.

33981721 is a deficient number, since it is larger than the sum of its proper divisors (1).

33981721 is an equidigital number, since it uses as much as digits as its factorization.

33981721 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 9072, while the sum is 34.

The square root of 33981721 is about 5829.3842728027. The cubic root of 33981721 is about 323.9031139716.

The spelling of 33981721 in words is "thirty-three million, nine hundred eighty-one thousand, seven hundred twenty-one".