16921808251 has 2 divisors, whose sum is σ = 16921808252. Its totient is φ = 16921808250.

The previous prime is 16921808243. The next prime is 16921808257. The reversal of 16921808251 is 15280812961.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 16921808251 - 2³ = 16921808243 is a prime.

It is a super-2 number, since 2×16921808251² (a number of 21 digits) contains 22 as substring.

It is a junction number, because it is equal to n+sod(n) for n = 16921808198 and 16921808207.

It is not a weakly prime, because it can be changed into another prime (16921808257) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 8460904125 + 8460904126.

It is an arithmetic number, because the mean of its divisors is an integer number (8460904126).

Almost surely, 2^16921808251 is an apocalyptic number.

16921808251 is a deficient number, since it is larger than the sum of its proper divisors (1).

16921808251 is an equidigital number, since it uses as much as digits as its factorization.

16921808251 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 69120, while the sum is 43.

The spelling of 16921808251 in words is "sixteen billion, nine hundred twenty-one million, eight hundred eight thousand, two hundred fifty-one".