16901821 has 2 divisors, whose sum is σ = 16901822. Its totient is φ = 16901820.

The previous prime is 16901777. The next prime is 16901831. The reversal of 16901821 is 12810961.

It is a happy number.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 11088900 + 5812921 = 3330^2 + 2411^2 .

It is an emirp because it is prime and its reverse (12810961) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 16901821 - 2⁹ = 16901309 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 16901821.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (16901831) 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, 8450910 + 8450911.

It is an arithmetic number, because the mean of its divisors is an integer number (8450911).

Almost surely, 2^16901821 is an apocalyptic number.

It is an amenable number.

16901821 is a deficient number, since it is larger than the sum of its proper divisors (1).

16901821 is an equidigital number, since it uses as much as digits as its factorization.

16901821 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 864, while the sum is 28.

The square root of 16901821 is about 4111.1824333153. The cubic root of 16901821 is about 256.6322112254.

The spelling of 16901821 in words is "sixteen million, nine hundred one thousand, eight hundred twenty-one".