30721745 has 4 divisors (see below), whose sum is σ = 36866100. Its totient is φ = 24577392.

The previous prime is 30721741. The next prime is 30721753. The reversal of 30721745 is 54712703.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 3806401 + 26915344 = 1951^2 + 5188^2 .

It is a cyclic number.

It is not a de Polignac number, because 30721745 - 2² = 30721741 is a prime.

It is not an unprimeable number, because it can be changed into a prime (30721741) 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 in 3 ways as a sum of consecutive naturals, for example, 3072170 + ... + 3072179.

It is an arithmetic number, because the mean of its divisors is an integer number (9216525).

Almost surely, 2^30721745 is an apocalyptic number.

It is an amenable number.

30721745 is a deficient number, since it is larger than the sum of its proper divisors (6144355).

30721745 is an equidigital number, since it uses as much as digits as its factorization.

30721745 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 6144354.

The product of its (nonzero) digits is 5880, while the sum is 29.

The square root of 30721745 is about 5542.7200001443. The cubic root of 30721745 is about 313.1953412542.

The spelling of 30721745 in words is "thirty million, seven hundred twenty-one thousand, seven hundred forty-five".