21198782681 has 8 divisors (see below), whose sum is σ = 21356488704. Its totient is φ = 21041563680.

The previous prime is 21198782677. The next prime is 21198782719. The reversal of 21198782681 is 18628789112.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 21198782681 - 2² = 21198782677 is a prime.

It is a super-2 number, since 2×21198782681² (a number of 21 digits) contains 22 as substring.

It is a Duffinian number.

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (21198782081) 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 7 ways as a sum of consecutive naturals, for example, 34145 + ... + 208718.

It is an arithmetic number, because the mean of its divisors is an integer number (2669561088).

Almost surely, 2^21198782681 is an apocalyptic number.

It is an amenable number.

21198782681 is a deficient number, since it is larger than the sum of its proper divisors (157706023).

21198782681 is a wasteful number, since it uses less digits than its factorization.

21198782681 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 243511.

The product of its digits is 774144, while the sum is 53.

The spelling of 21198782681 in words is "twenty-one billion, one hundred ninety-eight million, seven hundred eighty-two thousand, six hundred eighty-one".