16787821 has 2 divisors, whose sum is σ = 16787822. Its totient is φ = 16787820.

The previous prime is 16787807. The next prime is 16787831. The reversal of 16787821 is 12878761.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 11634921 + 5152900 = 3411^2 + 2270^2 .

It is a cyclic number.

It is not a de Polignac number, because 16787821 - 2¹¹ = 16785773 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (16787831) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 8393910 + 8393911.

It is an arithmetic number, because the mean of its divisors is an integer number (8393911).

Almost surely, 2^16787821 is an apocalyptic number.

It is an amenable number.

16787821 is a deficient number, since it is larger than the sum of its proper divisors (1).

16787821 is an equidigital number, since it uses as much as digits as its factorization.

16787821 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 37632, while the sum is 40.

The square root of 16787821 is about 4097.2943511542. The cubic root of 16787821 is about 256.0539284581.

The spelling of 16787821 in words is "sixteen million, seven hundred eighty-seven thousand, eight hundred twenty-one".