16972721 has 2 divisors, whose sum is σ = 16972722. Its totient is φ = 16972720.

The previous prime is 16972699. The next prime is 16972723. The reversal of 16972721 is 12727961.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 9333025 + 7639696 = 3055^2 + 2764^2 .

It is a cyclic number.

It is not a de Polignac number, because 16972721 - 2¹⁴ = 16956337 is a prime.

Together with 16972723, it forms a pair of twin primes.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (16972723) 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, 8486360 + 8486361.

It is an arithmetic number, because the mean of its divisors is an integer number (8486361).

Almost surely, 2^16972721 is an apocalyptic number.

It is an amenable number.

16972721 is a deficient number, since it is larger than the sum of its proper divisors (1).

16972721 is an equidigital number, since it uses as much as digits as its factorization.

16972721 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 10584, while the sum is 35.

The square root of 16972721 is about 4119.7962328251. The cubic root of 16972721 is about 256.9905521213.

The spelling of 16972721 in words is "sixteen million, nine hundred seventy-two thousand, seven hundred twenty-one".