16551281 has 2 divisors, whose sum is σ = 16551282. Its totient is φ = 16551280.

The previous prime is 16551263. The next prime is 16551287. The reversal of 16551281 is 18215561.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 8761600 + 7789681 = 2960^2 + 2791^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-16551281 is a prime.

It is a super-2 number, since 2×16551281² = 547889805481922, which contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (16551287) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 8275640 + 8275641.

It is an arithmetic number, because the mean of its divisors is an integer number (8275641).

Almost surely, 2^16551281 is an apocalyptic number.

It is an amenable number.

16551281 is a deficient number, since it is larger than the sum of its proper divisors (1).

16551281 is an equidigital number, since it uses as much as digits as its factorization.

16551281 is an evil number, because the sum of its binary digits is even.

The product of its digits is 2400, while the sum is 29.

The square root of 16551281 is about 4068.3265601473. The cubic root of 16551281 is about 254.8456377059.

The spelling of 16551281 in words is "sixteen million, five hundred fifty-one thousand, two hundred eighty-one".