16541981 has 2 divisors, whose sum is σ = 16541982. Its totient is φ = 16541980.

The previous prime is 16541963. The next prime is 16542017. The reversal of 16541981 is 18914561.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 15405625 + 1136356 = 3925^2 + 1066^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-16541981 is a prime.

It is a super-2 number, since 2×16541981² = 547274270808722, which contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (16543981) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 8270990 + 8270991.

It is an arithmetic number, because the mean of its divisors is an integer number (8270991).

Almost surely, 2^16541981 is an apocalyptic number.

It is an amenable number.

16541981 is a deficient number, since it is larger than the sum of its proper divisors (1).

16541981 is an equidigital number, since it uses as much as digits as its factorization.

16541981 is an evil number, because the sum of its binary digits is even.

The product of its digits is 8640, while the sum is 35.

The square root of 16541981 is about 4067.1834234517. The cubic root of 16541981 is about 254.7978970209.

The spelling of 16541981 in words is "sixteen million, five hundred forty-one thousand, nine hundred eighty-one".