26216721981 has 16 divisors (see below), whose sum is σ = 38962123200. Its totient is φ = 17422673904.

The previous prime is 26216721967. The next prime is 26216721991. The reversal of 26216721981 is 18912761262.

26216721981 is a `hidden beast` number, since 2 + 621 + 6 + 7 + 2 + 19 + 8 + 1 = 666.

It is not a de Polignac number, because 26216721981 - 2⁹ = 26216721469 is a prime.

It is a super-2 number, since 2×26216721981² (a number of 22 digits) contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (26216721931) 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 15 ways as a sum of consecutive naturals, for example, 1522971 + ... + 1540088.

It is an arithmetic number, because the mean of its divisors is an integer number (2435132700).

Almost surely, 2^26216721981 is an apocalyptic number.

It is an amenable number.

26216721981 is a deficient number, since it is larger than the sum of its proper divisors (12745401219).

26216721981 is a wasteful number, since it uses less digits than its factorization.

26216721981 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3063385 (or 3063379 counting only the distinct ones).

The product of its digits is 145152, while the sum is 45.

The spelling of 26216721981 in words is "twenty-six billion, two hundred sixteen million, seven hundred twenty-one thousand, nine hundred eighty-one".