16860721 has 2 divisors, whose sum is σ = 16860722. Its totient is φ = 16860720.

The previous prime is 16860709. The next prime is 16860743. The reversal of 16860721 is 12706861.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 9678321 + 7182400 = 3111^2 + 2680^2 .

It is a cyclic number.

It is not a de Polignac number, because 16860721 - 2⁷ = 16860593 is a prime.

It is not a weakly prime, because it can be changed into another prime (16860761) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 8430360 + 8430361.

It is an arithmetic number, because the mean of its divisors is an integer number (8430361).

Almost surely, 2^16860721 is an apocalyptic number.

It is an amenable number.

16860721 is a deficient number, since it is larger than the sum of its proper divisors (1).

16860721 is an equidigital number, since it uses as much as digits as its factorization.

16860721 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 4032, while the sum is 31.

The square root of 16860721 is about 4106.1808289456. The cubic root of 16860721 is about 256.4240256707.

The spelling of 16860721 in words is "sixteen million, eight hundred sixty thousand, seven hundred twenty-one".