16442821 has 2 divisors, whose sum is σ = 16442822. Its totient is φ = 16442820.

The previous prime is 16442807. The next prime is 16442827. The reversal of 16442821 is 12824461.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 16112196 + 330625 = 4014^2 + 575^2 .

It is a cyclic number.

It is not a de Polignac number, because 16442821 - 2⁷ = 16442693 is a prime.

It is a super-3 number, since 3×16442821³ (a number of 23 digits) contains 333 as substring.

It is a self number, because there is not a number n which added to its sum of digits gives 16442821.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (16442827) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 8221410 + 8221411.

It is an arithmetic number, because the mean of its divisors is an integer number (8221411).

Almost surely, 2^16442821 is an apocalyptic number.

It is an amenable number.

16442821 is a deficient number, since it is larger than the sum of its proper divisors (1).

16442821 is an equidigital number, since it uses as much as digits as its factorization.

16442821 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 3072, while the sum is 28.

The square root of 16442821 is about 4054.9748457913. The cubic root of 16442821 is about 254.2877522967.

It can be divided in two parts, 1644 and 2821, that added together give a triangular number (4465 = T₉₄).

The spelling of 16442821 in words is "sixteen million, four hundred forty-two thousand, eight hundred twenty-one".