21518842861 has 8 divisors (see below), whose sum is σ = 21829870944. Its totient is φ = 21209047440.

The previous prime is 21518842823. The next prime is 21518842889. The reversal of 21518842861 is 16824881512.

It is a happy number.

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 21518842861 - 2⁹ = 21518842349 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 (21518822861) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 272971 + ... + 342856.

It is an arithmetic number, because the mean of its divisors is an integer number (2728733868).

Almost surely, 2^21518842861 is an apocalyptic number.

It is an amenable number.

21518842861 is a deficient number, since it is larger than the sum of its proper divisors (311028083).

21518842861 is an equidigital number, since it uses as much as digits as its factorization.

21518842861 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 616331.

The product of its digits is 245760, while the sum is 46.

The spelling of 21518842861 in words is "twenty-one billion, five hundred eighteen million, eight hundred forty-two thousand, eight hundred sixty-one".