26197911981 has 24 divisors (see below), whose sum is σ = 39211652480. Its totient is φ = 16843147776.

The previous prime is 26197911947. The next prime is 26197912007. The reversal of 26197911981 is 18911979162.

26197911981 is a `hidden beast` number, since 2 + 619 + 7 + 9 + 1 + 19 + 8 + 1 = 666.

It is not a de Polignac number, because 26197911981 - 2⁷ = 26197911853 is a prime.

It is a super-2 number, since 2×26197911981² (a number of 22 digits) contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (26197913981) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 397876 + ... + 459021.

Almost surely, 2^26197911981 is an apocalyptic number.

It is an amenable number.

26197911981 is a deficient number, since it is larger than the sum of its proper divisors (13013740499).

26197911981 is a wasteful number, since it uses less digits than its factorization.

26197911981 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 857025 (or 857022 counting only the distinct ones).

The product of its digits is 489888, while the sum is 54.

The spelling of 26197911981 in words is "twenty-six billion, one hundred ninety-seven million, nine hundred eleven thousand, nine hundred eighty-one".