16140721 has 2 divisors, whose sum is σ = 16140722. Its totient is φ = 16140720.

The previous prime is 16140679. The next prime is 16140731. The reversal of 16140721 is 12704161.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 14288400 + 1852321 = 3780^2 + 1361^2 .

It is an emirp because it is prime and its reverse (12704161) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 16140721 - 2⁹ = 16140209 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 16140692 and 16140701.

It is not a weakly prime, because it can be changed into another prime (16140731) 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 as a sum of consecutive naturals, namely, 8070360 + 8070361.

It is an arithmetic number, because the mean of its divisors is an integer number (8070361).

Almost surely, 2^16140721 is an apocalyptic number.

It is an amenable number.

16140721 is a deficient number, since it is larger than the sum of its proper divisors (1).

16140721 is an equidigital number, since it uses as much as digits as its factorization.

16140721 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 336, while the sum is 22.

The square root of 16140721 is about 4017.5516175900. The cubic root of 16140721 is about 252.7207937063.

Adding to 16140721 its reverse (12704161), we get a palindrome (28844882).

It can be divided in two parts, 16140 and 721, that added together give a palindrome (16861).

The spelling of 16140721 in words is "sixteen million, one hundred forty thousand, seven hundred twenty-one".