21958717861 has 8 divisors (see below), whose sum is σ = 22484496384. Its totient is φ = 21435379920.

The previous prime is 21958717853. The next prime is 21958717871. The reversal of 21958717861 is 16871785912.

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 21958717861 - 2³ = 21958717853 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21958717801) 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, 591930 + ... + 627931.

It is an arithmetic number, because the mean of its divisors is an integer number (2810562048).

Almost surely, 2^21958717861 is an apocalyptic number.

It is an amenable number.

21958717861 is a deficient number, since it is larger than the sum of its proper divisors (525778523).

21958717861 is a wasteful number, since it uses less digits than its factorization.

21958717861 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1220291.

The product of its digits is 1693440, while the sum is 55.

The spelling of 21958717861 in words is "twenty-one billion, nine hundred fifty-eight million, seven hundred seventeen thousand, eight hundred sixty-one".