16555381 has 2 divisors, whose sum is σ = 16555382. Its totient is φ = 16555380.

The previous prime is 16555373. The next prime is 16555393. The reversal of 16555381 is 18355561.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 16402500 + 152881 = 4050^2 + 391^2 .

It is a cyclic number.

It is not a de Polignac number, because 16555381 - 2³ = 16555373 is a prime.

It is a super-2 number, since 2×16555381² = 548161280110322, which contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (16555351) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 8277690 + 8277691.

It is an arithmetic number, because the mean of its divisors is an integer number (8277691).

Almost surely, 2^16555381 is an apocalyptic number.

It is an amenable number.

16555381 is a deficient number, since it is larger than the sum of its proper divisors (1).

16555381 is an equidigital number, since it uses as much as digits as its factorization.

16555381 is an evil number, because the sum of its binary digits is even.

The product of its digits is 18000, while the sum is 34.

The square root of 16555381 is about 4068.8304216322. The cubic root of 16555381 is about 254.8666789947.

The spelling of 16555381 in words is "sixteen million, five hundred fifty-five thousand, three hundred eighty-one".