16861981971 has 4 divisors (see below), whose sum is σ = 22482642632. Its totient is φ = 11241321312.

The previous prime is 16861981967. The next prime is 16861981999. The reversal of 16861981971 is 17918916861.

It is a semiprime because it is the product of two primes.

It is not a de Polignac number, because 16861981971 - 2² = 16861981967 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (16861981921) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 2810330326 + ... + 2810330331.

It is an arithmetic number, because the mean of its divisors is an integer number (5620660658).

Almost surely, 2^16861981971 is an apocalyptic number.

16861981971 is a deficient number, since it is larger than the sum of its proper divisors (5620660661).

16861981971 is an equidigital number, since it uses as much as digits as its factorization.

16861981971 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 5620660660.

The product of its digits is 1306368, while the sum is 57.

The spelling of 16861981971 in words is "sixteen billion, eight hundred sixty-one million, nine hundred eighty-one thousand, nine hundred seventy-one".