16906251991 has 2 divisors, whose sum is σ = 16906251992. Its totient is φ = 16906251990.

The previous prime is 16906251877. The next prime is 16906251997. The reversal of 16906251991 is 19915260961.

It is a strong prime.

It is an emirp because it is prime and its reverse (19915260961) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 16906251991 - 2¹⁵ = 16906219223 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (16906251997) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 8453125995 + 8453125996.

It is an arithmetic number, because the mean of its divisors is an integer number (8453125996).

Almost surely, 2^16906251991 is an apocalyptic number.

16906251991 is a deficient number, since it is larger than the sum of its proper divisors (1).

16906251991 is an equidigital number, since it uses as much as digits as its factorization.

16906251991 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 262440, while the sum is 49.

The spelling of 16906251991 in words is "sixteen billion, nine hundred six million, two hundred fifty-one thousand, nine hundred ninety-one".