16257721 has 2 divisors, whose sum is σ = 16257722. Its totient is φ = 16257720.

The previous prime is 16257701. The next prime is 16257737. The reversal of 16257721 is 12775261.

16257721 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 15492096 + 765625 = 3936^2 + 875^2 .

It is a cyclic number.

It is not a de Polignac number, because 16257721 - 2⁹ = 16257209 is a prime.

It is a super-2 number, since 2×16257721² = 528626984227682, which contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (16257701) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 8128860 + 8128861.

It is an arithmetic number, because the mean of its divisors is an integer number (8128861).

Almost surely, 2^16257721 is an apocalyptic number.

It is an amenable number.

16257721 is a deficient number, since it is larger than the sum of its proper divisors (1).

16257721 is an equidigital number, since it uses as much as digits as its factorization.

16257721 is an evil number, because the sum of its binary digits is even.

The product of its digits is 5880, while the sum is 31.

The square root of 16257721 is about 4032.0864326053. The cubic root of 16257721 is about 253.3299605199.

The spelling of 16257721 in words is "sixteen million, two hundred fifty-seven thousand, seven hundred twenty-one".