16991396381 has 2 divisors, whose sum is σ = 16991396382. Its totient is φ = 16991396380.

The previous prime is 16991396369. The next prime is 16991396407. The reversal of 16991396381 is 18369319961.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 16164833881 + 826562500 = 127141^2 + 28750^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-16991396381 is a prime.

It is a super-3 number, since 3×16991396381³ (a number of 32 digits) contains 333 as substring. Note that it is a super-d number also for d = 2.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (16991396321) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 8495698190 + 8495698191.

It is an arithmetic number, because the mean of its divisors is an integer number (8495698191).

Almost surely, 2^16991396381 is an apocalyptic number.

It is an amenable number.

16991396381 is a deficient number, since it is larger than the sum of its proper divisors (1).

16991396381 is an equidigital number, since it uses as much as digits as its factorization.

16991396381 is an evil number, because the sum of its binary digits is even.

The product of its digits is 1889568, while the sum is 56.

The spelling of 16991396381 in words is "sixteen billion, nine hundred ninety-one million, three hundred ninety-six thousand, three hundred eighty-one".