16627981 has 2 divisors, whose sum is σ = 16627982. Its totient is φ = 16627980.

The previous prime is 16627979. The next prime is 16628009. The reversal of 16627981 is 18972661.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 12180100 + 4447881 = 3490^2 + 2109^2 .

It is an emirp because it is prime and its reverse (18972661) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 16627981 - 2¹ = 16627979 is a prime.

It is a super-2 number, since 2×16627981² = 552979504272722, which contains 22 as substring.

Together with 16627979, it forms a pair of twin primes.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (16627901) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 8313990 + 8313991.

It is an arithmetic number, because the mean of its divisors is an integer number (8313991).

Almost surely, 2^16627981 is an apocalyptic number.

It is an amenable number.

16627981 is a deficient number, since it is larger than the sum of its proper divisors (1).

16627981 is an equidigital number, since it uses as much as digits as its factorization.

16627981 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 36288, while the sum is 40.

The square root of 16627981 is about 4077.7421448640. The cubic root of 16627981 is about 255.2386897461.

The spelling of 16627981 in words is "sixteen million, six hundred twenty-seven thousand, nine hundred eighty-one".