30405721 has 2 divisors, whose sum is σ = 30405722. Its totient is φ = 30405720.

The previous prime is 30405691. The next prime is 30405731. The reversal of 30405721 is 12750403.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 29550096 + 855625 = 5436^2 + 925^2 .

It is a cyclic number.

It is not a de Polignac number, because 30405721 - 2⁷ = 30405593 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 30405692 and 30405701.

It is not a weakly prime, because it can be changed into another prime (30405731) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 15202860 + 15202861.

It is an arithmetic number, because the mean of its divisors is an integer number (15202861).

Almost surely, 2^30405721 is an apocalyptic number.

It is an amenable number.

30405721 is a deficient number, since it is larger than the sum of its proper divisors (1).

30405721 is an equidigital number, since it uses as much as digits as its factorization.

30405721 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 840, while the sum is 22.

The square root of 30405721 is about 5514.1382826331. The cubic root of 30405721 is about 312.1177269127.

The spelling of 30405721 in words is "thirty million, four hundred five thousand, seven hundred twenty-one".