21115639553 has 8 divisors (see below), whose sum is σ = 22041699840. Its totient is φ = 20204886240.

The previous prime is 21115639547. The next prime is 21115639609. The reversal of 21115639553 is 35593651112.

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 21115639553 - 2¹⁴ = 21115623169 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is a self number, because there is not a number n which added to its sum of digits gives 21115639553.

It is not an unprimeable number, because it can be changed into a prime (21115639543) 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, 3823925 + ... + 3829442.

It is an arithmetic number, because the mean of its divisors is an integer number (2755212480).

Almost surely, 2^21115639553 is an apocalyptic number.

It is an amenable number.

21115639553 is a deficient number, since it is larger than the sum of its proper divisors (926060287).

21115639553 is an equidigital number, since it uses as much as digits as its factorization.

21115639553 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 7653487.

The product of its digits is 121500, while the sum is 41.

The spelling of 21115639553 in words is "twenty-one billion, one hundred fifteen million, six hundred thirty-nine thousand, five hundred fifty-three".