30721939 has 2 divisors, whose sum is σ = 30721940. Its totient is φ = 30721938.

The previous prime is 30721871. The next prime is 30721963. The reversal of 30721939 is 93912703.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 30721939 - 2¹¹ = 30719891 is a prime.

It is not a weakly prime, because it can be changed into another prime (30721969) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 15360969 + 15360970.

It is an arithmetic number, because the mean of its divisors is an integer number (15360970).

Almost surely, 2^30721939 is an apocalyptic number.

30721939 is a deficient number, since it is larger than the sum of its proper divisors (1).

30721939 is an equidigital number, since it uses as much as digits as its factorization.

30721939 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 10206, while the sum is 34.

The square root of 30721939 is about 5542.7375005497. The cubic root of 30721939 is about 313.1960005024.

The spelling of 30721939 in words is "thirty million, seven hundred twenty-one thousand, nine hundred thirty-nine".