16648981 has 2 divisors, whose sum is σ = 16648982. Its totient is φ = 16648980.

The previous prime is 16648949. The next prime is 16648991. The reversal of 16648981 is 18984661.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 14945956 + 1703025 = 3866^2 + 1305^2 .

It is an emirp because it is prime and its reverse (18984661) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 16648981 - 2⁵ = 16648949 is a prime.

It is a super-2 number, since 2×16648981² = 554377136676722, which contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (16648901) 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, 8324490 + 8324491.

It is an arithmetic number, because the mean of its divisors is an integer number (8324491).

Almost surely, 2^16648981 is an apocalyptic number.

It is an amenable number.

16648981 is a deficient number, since it is larger than the sum of its proper divisors (1).

16648981 is an equidigital number, since it uses as much as digits as its factorization.

16648981 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 82944, while the sum is 43.

The square root of 16648981 is about 4080.3162867601. The cubic root of 16648981 is about 255.3460941993.

The spelling of 16648981 in words is "sixteen million, six hundred forty-eight thousand, nine hundred eighty-one".